diff --git a/Cargo.lock b/Cargo.lock
index a80a5ee62b5..e32b0b4d406 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -958,12 +958,6 @@ dependencies = [
  "syn",
 ]
 
-[[package]]
-name = "fs_extra"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2022715d62ab30faffd124d40b76f4134a550a87792276512b18d63272333394"
-
 [[package]]
 name = "fuchsia-cprng"
 version = "0.1.1"
@@ -1549,9 +1543,9 @@ dependencies = [
 
 [[package]]
 name = "mimalloc-rust"
-version = "0.1.5"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bcc30df9dfdb5bb6cb2470de65ca604c3eaa3e5dc2ad02a9a98f567df5844472"
+checksum = "6973866e0bc6504c03a16b6817b7e70839cc8a1dbd5d6dab00c65d8034868d8b"
 dependencies = [
  "cty",
  "mimalloc-rust-sys",
@@ -1559,9 +1553,9 @@ dependencies = [
 
 [[package]]
 name = "mimalloc-rust-sys"
-version = "1.7.3-source"
+version = "1.7.6-source"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3adc8731262b982f4e0860770dba118305cafe1b2e7ebe95b29b2c2f46a70666"
+checksum = "7a50daf45336b979a202a19f53b4b382f2c4bd50f392a8dbdb4c6c56ba5dfa64"
 dependencies = [
  "cc",
  "cty",
@@ -3407,6 +3401,7 @@ dependencies = [
  "backtrace",
  "criterion",
  "indexmap",
+ "num_cpus",
  "once_cell",
  "parking_lot",
  "pretty_assertions",
@@ -4023,7 +4018,6 @@ name = "swc_node_base"
 version = "0.5.5"
 dependencies = [
  "mimalloc-rust",
- "tikv-jemallocator",
 ]
 
 [[package]]
@@ -4339,27 +4333,6 @@ dependencies = [
  "once_cell",
 ]
 
-[[package]]
-name = "tikv-jemalloc-sys"
-version = "0.4.3+5.2.1-patched.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1792ccb507d955b46af42c123ea8863668fae24d03721e40cad6a41773dbb49"
-dependencies = [
- "cc",
- "fs_extra",
- "libc",
-]
-
-[[package]]
-name = "tikv-jemallocator"
-version = "0.4.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5b7bcecfafe4998587d636f9ae9d55eb9d0499877b88757767c346875067098"
-dependencies = [
- "libc",
- "tikv-jemalloc-sys",
-]
-
 [[package]]
 name = "time"
 version = "0.1.43"
diff --git a/Cargo.toml b/Cargo.toml
index 1812d382823..7562d53239a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,7 +23,7 @@ members = [
 ]
 
 [profile.release]
-codegen-units = 1
+lto = true
 
 # We use CARGO_PROFILE_RELEASE_LTO for production builds
 # lto = "fat"
@@ -32,7 +32,7 @@ codegen-units = 1
 # opt-level = 'z'
 
 [profile.bench]
-codegen-units = 1
+lto = true
 debug = true
 
 # Without this, printing diff consumes more than a minute.
@@ -44,5 +44,5 @@ opt-level = 3
 opt-level = 3
 
 [patch.crates-io]
-cranelift-codegen = {git = "https://github.com/kdy1/wasmtime", branch = "tls"}
-cranelift-entity = {git = "https://github.com/kdy1/wasmtime", branch = "tls"}
+cranelift-codegen = { git = "https://github.com/kdy1/wasmtime", branch = "tls" }
+cranelift-entity = { git = "https://github.com/kdy1/wasmtime", branch = "tls" }
diff --git a/crates/swc_ecma_minifier/Cargo.toml b/crates/swc_ecma_minifier/Cargo.toml
index b51b24e7685..ac15dfab439 100644
--- a/crates/swc_ecma_minifier/Cargo.toml
+++ b/crates/swc_ecma_minifier/Cargo.toml
@@ -25,6 +25,7 @@ ahash = "0.7.6"
 arrayvec = "0.7.2"
 backtrace = { version = "0.3.61", optional = true }
 indexmap = "1.7.0"
+num_cpus = "1.13.1"
 once_cell = "1.10.0"
 parking_lot = "0.12.0"
 pretty_assertions = { version = "1.1", optional = true }
diff --git a/crates/swc_ecma_minifier/src/analyzer/mod.rs b/crates/swc_ecma_minifier/src/analyzer/mod.rs
index c7d2c8850d7..211d1d79616 100644
--- a/crates/swc_ecma_minifier/src/analyzer/mod.rs
+++ b/crates/swc_ecma_minifier/src/analyzer/mod.rs
@@ -1,4 +1,6 @@
-use rustc_hash::{FxHashMap, FxHashSet};
+use std::{collections::HashSet, hash::BuildHasherDefault};
+
+use rustc_hash::{FxHashMap, FxHashSet, FxHasher};
 use swc_atoms::{js_word, JsWord};
 use swc_common::{collections::AHashSet, SyntaxContext};
 use swc_ecma_ast::*;
@@ -163,35 +165,41 @@ pub(crate) struct ProgramData {
 impl ProgramData {
     pub(crate) fn expand_infected(
         &self,
-        ids: impl IntoIterator<Item = Id>,
+        ids: FxHashSet<Id>,
         max_num: usize,
     ) -> Result<FxHashSet<Id>, ()> {
-        let mut result = FxHashSet::default();
-        self.expand_infected_inner(ids, max_num, &mut result)?;
-        Ok(result)
-    }
-
-    fn expand_infected_inner(
-        &self,
-        ids: impl IntoIterator<Item = Id>,
-        max_num: usize,
-        result: &mut FxHashSet<Id>,
-    ) -> Result<(), ()> {
-        for id in ids {
-            if !result.insert(id.clone()) {
-                continue;
+        let init =
+            HashSet::with_capacity_and_hasher(max_num, BuildHasherDefault::<FxHasher>::default());
+        ids.into_iter().try_fold(init, |mut res, id| {
+            let mut ids = Vec::with_capacity(max_num);
+            ids.push(id);
+            let mut ranges = vec![0..1usize];
+            loop {
+                let range = ranges.remove(0);
+                for index in range {
+                    let iid = ids.get(index).unwrap();
+                    if !res.insert(iid.clone()) {
+                        continue;
+                    }
+                    if res.len() >= max_num {
+                        return Err(());
+                    }
+                    if let Some(info) = self.vars.get(iid) {
+                        let infects = &info.infects;
+                        if !infects.is_empty() {
+                            let old_len = ids.len();
+                            ids.extend_from_slice(infects.as_slice());
+                            let new_len = ids.len();
+                            ranges.push(old_len..new_len);
+                        }
+                    }
+                }
+                if ranges.is_empty() {
+                    break;
+                }
             }
-            if result.len() >= max_num {
-                return Err(());
-            }
-
-            if let Some(info) = self.vars.get(&id) {
-                let ids = info.infects.clone();
-                self.expand_infected_inner(ids, max_num, result)?;
-            }
-        }
-
-        Ok(())
+            Ok(res)
+        })
     }
 
     pub(crate) fn contains_unresolved(&self, e: &Expr) -> bool {
@@ -633,7 +641,8 @@ where
         e.visit_children_with(&mut *self.with_ctx(ctx));
 
         if let Expr::Ident(i) = e {
-            if cfg!(feature = "debug") {
+            #[cfg(feature = "debug")]
+            {
                 // debug!(
                 //     "Usage: `{}``; update = {:?}, assign_lhs = {:?} ",
                 //     i,
diff --git a/crates/swc_ecma_minifier/src/compress/hoist_decls.rs b/crates/swc_ecma_minifier/src/compress/hoist_decls.rs
index 229ed5eb8d7..9e6a0bf631a 100644
--- a/crates/swc_ecma_minifier/src/compress/hoist_decls.rs
+++ b/crates/swc_ecma_minifier/src/compress/hoist_decls.rs
@@ -1,3 +1,4 @@
+use rayon::prelude::*;
 use swc_common::{collections::AHashSet, pass::Repeated, util::take::Take, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_utils::{find_pat_ids, StmtLike};
@@ -6,7 +7,7 @@ use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith, VisitWith};
 use super::util::drop_invalid_stmts;
 use crate::{
     analyzer::{ProgramData, UsageAnalyzer},
-    util::{is_hoisted_var_decl_without_init, sort::is_sorted_by_key, IsModuleItem, ModuleItemExt},
+    util::{is_hoisted_var_decl_without_init, sort::is_sorted_by, IsModuleItem, ModuleItemExt},
 };
 
 pub(super) struct DeclHoisterConfig {
@@ -46,33 +47,43 @@ impl Hoister<'_> {
         Vec<T>: for<'aa> VisitMutWith<Hoister<'aa>> + VisitWith<UsageAnalyzer>,
     {
         stmts.visit_mut_children_with(self);
+        let len = stmts.len();
+        let should_hoist = !is_sorted_by(
+            stmts.iter().map(|stmt| match stmt.as_stmt() {
+                Some(stmt) => match stmt {
+                    Stmt::Decl(Decl::Fn(..)) if self.config.hoist_fns => 1,
+                    Stmt::Decl(Decl::Var(var)) if self.config.hoist_vars => {
+                        let ids: Vec<Id> = find_pat_ids(&var.decls);
 
-        let should_hoist = !is_sorted_by_key(stmts.iter(), |stmt| match stmt.as_stmt() {
-            Some(stmt) => match stmt {
-                Stmt::Decl(Decl::Fn(..)) if self.config.hoist_fns => 1,
-                Stmt::Decl(Decl::Var(var)) if self.config.hoist_vars => {
-                    let ids: Vec<Id> = find_pat_ids(&var.decls);
-
-                    if ids.iter().any(|id| {
-                        self.data
-                            .vars
-                            .get(id)
-                            .map(|v| !v.used_above_decl)
-                            .unwrap_or(false)
-                    }) {
-                        2
-                    } else {
-                        3
+                        if ids.iter().any(|id| {
+                            self.data
+                                .vars
+                                .get(id)
+                                .map(|v| !v.used_above_decl)
+                                .unwrap_or(false)
+                        }) {
+                            2
+                        } else {
+                            3
+                        }
                     }
-                }
-                _ => 3,
-            },
-            None => 3,
-        }) || (self.config.hoist_vars
-            && stmts.windows(2).any(|stmts| {
-                is_hoisted_var_decl_without_init(&stmts[0])
-                    && is_hoisted_var_decl_without_init(&stmts[1])
-            }));
+                    _ => 3,
+                },
+                None => 3,
+            }),
+            PartialOrd::partial_cmp,
+        ) || (self.config.hoist_vars
+            && if len >= *crate::LIGHT_TASK_PARALLELS {
+                stmts.par_chunks(2).any(|stmts| {
+                    is_hoisted_var_decl_without_init(&stmts[0])
+                        && is_hoisted_var_decl_without_init(&stmts[1])
+                })
+            } else {
+                stmts.windows(2).any(|stmts| {
+                    is_hoisted_var_decl_without_init(&stmts[0])
+                        && is_hoisted_var_decl_without_init(&stmts[1])
+                })
+            });
 
         if !should_hoist {
             return;
diff --git a/crates/swc_ecma_minifier/src/compress/mod.rs b/crates/swc_ecma_minifier/src/compress/mod.rs
index 6ee0b33379c..38a83895509 100644
--- a/crates/swc_ecma_minifier/src/compress/mod.rs
+++ b/crates/swc_ecma_minifier/src/compress/mod.rs
@@ -1,8 +1,9 @@
+#[cfg(feature = "debug")]
+use std::thread;
 use std::{
     borrow::Cow,
     fmt,
     fmt::{Debug, Display, Formatter, Write},
-    thread,
     time::Instant,
 };
 
@@ -31,6 +32,7 @@ use crate::{
     compress::hoist_decls::decl_hoister,
     debug::{dump, AssertValid},
     marks::Marks,
+    maybe_par,
     mode::Mode,
     option::CompressOptions,
     util::{now, unit::CompileUnit, Optional},
@@ -107,14 +109,17 @@ where
         Vec<T>: VisitMutWith<Self> + for<'aa> VisitMutWith<hoist_decls::Hoister<'aa>>,
     {
         // Skip if `use asm` exists.
-        if stmts.iter().any(|stmt| match stmt.as_stmt() {
-            Some(Stmt::Expr(stmt)) => match &*stmt.expr {
-                // TODO improve check, directives can contain escaped characters
-                Expr::Lit(Lit::Str(Str { value, .. })) => &**value == "use asm",
+        if maybe_par!(
+            stmts.iter().any(|stmt| match stmt.as_stmt() {
+                Some(Stmt::Expr(stmt)) => match &*stmt.expr {
+                    // TODO improve check, directives can contain escaped characters
+                    Expr::Lit(Lit::Str(Str { value, .. })) => &**value == "use asm",
+                    _ => false,
+                },
                 _ => false,
-            },
-            _ => false,
-        }) {
+            }),
+            *crate::LIGHT_TASK_PARALLELS
+        ) {
             return;
         }
 
@@ -262,12 +267,11 @@ where
             }
         }
 
-        let start = if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        let start = {
             let start = n.dump();
             debug!("===== Start =====\n{}", start);
             start
-        } else {
-            String::new()
         };
 
         {
@@ -284,7 +288,8 @@ where
             self.changed |= visitor.changed();
             if visitor.changed() {
                 debug!("compressor: Simplified expressions");
-                if cfg!(feature = "debug") {
+                #[cfg(feature = "debug")]
+                {
                     debug!("===== Simplified =====\n{}", dump(&*n, false));
                 }
             }
@@ -299,7 +304,8 @@ where
                 );
             }
 
-            if cfg!(feature = "debug") && !visitor.changed() {
+            #[cfg(feature = "debug")]
+            if !visitor.changed() {
                 let simplified = n.dump();
                 if start != simplified {
                     assert_eq!(
@@ -322,6 +328,7 @@ where
                 PureOptimizerConfig {
                     enable_join_vars: self.pass > 1,
                     force_str_for_tpl: M::force_str_for_tpl(),
+                    #[cfg(feature = "debug")]
                     debug_infinite_loop: self.pass >= 20,
                 },
             );
@@ -329,13 +336,15 @@ where
 
             self.changed |= visitor.changed();
 
-            if cfg!(feature = "debug") && visitor.changed() {
+            #[cfg(feature = "debug")]
+            if visitor.changed() {
                 let src = n.dump();
                 debug!("===== After pure =====\n{}\n{}", start, src);
             }
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             n.visit_with(&mut AssertValid);
         }
 
@@ -364,11 +373,8 @@ where
         }
 
         if self.options.conditionals || self.options.dead_code {
-            let start = if cfg!(feature = "debug") {
-                dump(&*n, false)
-            } else {
-                "".into()
-            };
+            #[cfg(feature = "debug")]
+            let start = dump(&*n, false);
 
             let start_time = now();
 
@@ -385,7 +391,8 @@ where
                 );
             }
 
-            if cfg!(feature = "debug") {
+            #[cfg(feature = "debug")]
+            {
                 let simplified = dump(&*n, false);
 
                 if start != simplified {
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/arguments.rs b/crates/swc_ecma_minifier/src/compress/optimize/arguments.rs
index 43468da47d9..984169b0bf5 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/arguments.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/arguments.rs
@@ -90,10 +90,13 @@ where
         {
             // If a function has a variable named `arguments`, we abort.
             let data: Vec<Id> = find_pat_ids(&f.body);
-            for id in &data {
+            if data.iter().any(|id| {
                 if id.0 == js_word!("arguments") {
-                    return;
+                    return true;
                 }
+                false
+            }) {
+                return;
             }
         }
 
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/bools.rs b/crates/swc_ecma_minifier/src/compress/optimize/bools.rs
index 1e203dce855..de554befdb9 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/bools.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/bools.rs
@@ -7,9 +7,10 @@ use swc_ecma_utils::{
 };
 
 use super::Optimizer;
+#[cfg(feature = "debug")]
+use crate::debug::dump;
 use crate::{
     compress::{optimize::Ctx, util::negate_cost},
-    debug::dump,
     mode::Mode,
 };
 
@@ -67,6 +68,7 @@ where
             "bools: Negating: (!a && !b) => !(a || b) (because both expression are good for \
              negation)",
         );
+        #[cfg(feature = "debug")]
         let start = dump(&*e, false);
 
         e.op = if e.op == op!("&&") {
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/conditionals.rs b/crates/swc_ecma_minifier/src/compress/optimize/conditionals.rs
index ea93a828a04..e0252c3b972 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/conditionals.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/conditionals.rs
@@ -504,7 +504,7 @@ where
                     let mut args = vec![];
 
                     if cons.args.as_ref().map(|v| v.len()).unwrap_or(0) == 1 {
-                        args.push(ExprOrSpread {
+                        args = vec![ExprOrSpread {
                             spread: None,
                             expr: Box::new(Expr::Cond(CondExpr {
                                 span: DUMMY_SP,
@@ -512,7 +512,7 @@ where
                                 cons: cons.args.as_mut().unwrap()[0].expr.take(),
                                 alt: alt.args.as_mut().unwrap()[0].expr.take(),
                             })),
-                        });
+                        }];
                     }
 
                     report_change!(
@@ -715,10 +715,8 @@ where
             return;
         }
         //
-
-        let mut new_stmts = vec![];
-
-        for stmt in stmts.take() {
+        let mut new_stmts = Vec::with_capacity(stmts.len() * 2);
+        stmts.take().into_iter().for_each(|stmt| {
             match stmt.try_into_stmt() {
                 Ok(stmt) => match stmt {
                     Stmt::If(IfStmt {
@@ -753,7 +751,7 @@ where
                 },
                 Err(stmt) => new_stmts.push(stmt),
             }
-        }
+        });
 
         self.changed = true;
         report_change!("conditionals: Dropped useless `else` token");
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/evaluate.rs b/crates/swc_ecma_minifier/src/compress/optimize/evaluate.rs
index dc2c732b6a8..276f8c40340 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/evaluate.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/evaluate.rs
@@ -6,7 +6,7 @@ use swc_ecma_ast::*;
 use swc_ecma_utils::{undefined, ExprExt, Value::Known};
 
 use super::Optimizer;
-use crate::{compress::util::eval_as_number, mode::Mode, DISABLE_BUGGY_PASSES};
+use crate::{compress::util::eval_as_number, maybe_par, mode::Mode, DISABLE_BUGGY_PASSES};
 
 /// Methods related to the option `evaluate`.
 impl<M> Optimizer<'_, M>
@@ -399,12 +399,12 @@ where
                     match (ln.classify(), rn.classify()) {
                         (FpCategory::Zero, FpCategory::Zero) => {
                             // If a variable named `NaN` is in scope, don't convert e into NaN.
-                            if self
-                                .data
-                                .vars
-                                .iter()
-                                .any(|(name, v)| v.declared && name.0 == js_word!("NaN"))
-                            {
+                            let data = &self.data.vars;
+                            if maybe_par!(
+                                data.iter()
+                                    .any(|(name, v)| v.declared && name.0 == js_word!("NaN")),
+                                *crate::LIGHT_TASK_PARALLELS
+                            ) {
                                 return;
                             }
 
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/if_return.rs b/crates/swc_ecma_minifier/src/compress/optimize/if_return.rs
index 4ef0addb5f6..29b4849f76f 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/if_return.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/if_return.rs
@@ -4,7 +4,9 @@ use swc_ecma_utils::{undefined, StmtExt, StmtLike};
 use swc_ecma_visit::{noop_visit_type, Visit, VisitWith};
 
 use super::Optimizer;
-use crate::{compress::util::is_pure_undefined, debug::dump, mode::Mode, util::ExprOptExt};
+#[cfg(feature = "debug")]
+use crate::debug::dump;
+use crate::{compress::util::is_pure_undefined, mode::Mode, util::ExprOptExt};
 
 /// Methods related to the option `if_return`. All methods are noop if
 /// `if_return` is false.
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/iife.rs b/crates/swc_ecma_minifier/src/compress/optimize/iife.rs
index 368576b9779..aefa49a458f 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/iife.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/iife.rs
@@ -13,9 +13,10 @@ use super::{
     util::{MultiReplacer, MultiReplacerMode},
     Optimizer,
 };
+#[cfg(feature = "debug")]
+use crate::debug::dump;
 use crate::{
     compress::optimize::{util::Remapper, Ctx},
-    debug::dump,
     mode::Mode,
     util::{idents_captured_by, idents_used_by, make_number},
 };
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/inline.rs b/crates/swc_ecma_minifier/src/compress/optimize/inline.rs
index 667d26cdfb7..bc4172c7739 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/inline.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/inline.rs
@@ -6,7 +6,6 @@ use swc_ecma_utils::{find_pat_ids, ExprExt, IdentUsageFinder};
 use super::Optimizer;
 use crate::{
     compress::optimize::util::{class_has_side_effect, is_valid_for_lhs},
-    debug::dump,
     mode::Mode,
     util::{idents_captured_by, idents_used_by, idents_used_by_ignoring_nested},
 };
@@ -32,7 +31,7 @@ where
 
         trace_op!(
             "inline: store_var_for_inlining({}, should_preserve = {:?})",
-            dump(&var.name, false),
+            crate::debug::dump(&var.name, false),
             should_preserve
         );
 
@@ -66,7 +65,7 @@ where
                 if should_preserve && usage.var_kind != Some(VarDeclKind::Const) {
                     log_abort!(
                         "inline: [x] Preserving non-const variable `{}` because it's top-level",
-                        dump(&var.name, false)
+                        crate::debug::dump(&var.name, false)
                     );
                     return;
                 }
@@ -606,6 +605,7 @@ where
                 }
 
                 self.changed = true;
+                #[cfg(feature = "debug")]
                 match &decl {
                     Decl::Class(c) => {
                         report_change!(
@@ -711,7 +711,7 @@ where
 
                 *e = *value;
 
-                log_abort!("inline: [Change] {}", dump(&*e, false))
+                log_abort!("inline: [Change] {}", crate::debug::dump(&*e, false))
             }
         }
     }
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/mod.rs b/crates/swc_ecma_minifier/src/compress/optimize/mod.rs
index a4b38254514..9deddc01695 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/mod.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/mod.rs
@@ -14,6 +14,7 @@ use swc_ecma_utils::{
     Type, Value,
 };
 use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith, VisitWith};
+#[cfg(feature = "debug")]
 use tracing::{debug, span, Level};
 use Value::Known;
 
@@ -22,11 +23,14 @@ use self::{
     util::{MultiReplacer, MultiReplacerMode},
 };
 use super::util::{drop_invalid_stmts, is_fine_for_if_cons};
+#[cfg(feature = "debug")]
+use crate::debug::dump;
 use crate::{
     analyzer::{ProgramData, UsageAnalyzer},
     compress::util::is_pure_undefined,
-    debug::{dump, AssertValid},
+    debug::AssertValid,
     marks::Marks,
+    maybe_par,
     mode::Mode,
     option::CompressOptions,
     util::{
@@ -224,6 +228,7 @@ struct Optimizer<'a, M> {
 
     mode: &'a M,
 
+    #[allow(unused)]
     debug_infinite_loop: bool,
 
     functions: FxHashMap<Id, FnMetadata>,
@@ -351,10 +356,12 @@ where
                     // Don't set in_strict for directive itself.
                     stmt.visit_mut_with(self);
                 } else {
-                    stmt.visit_mut_with(&mut *self.with_ctx(child_ctx));
+                    let child_optimizer = &mut *self.with_ctx(child_ctx);
+                    stmt.visit_mut_with(child_optimizer);
                 }
 
-                if cfg!(debug_assertions) {
+                #[cfg(debug_assertions)]
+                {
                     stmt.visit_with(&mut AssertValid);
                 }
 
@@ -379,43 +386,50 @@ where
 
         self.ctx.in_asm |= use_asm;
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.reorder_stmts(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.merge_sequences_in_stmts(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.merge_similar_ifs(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.make_sequences(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.drop_else_token(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.break_assignments_in_seqs(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
@@ -978,6 +992,7 @@ where
                 span,
                 left,
                 right,
+                #[cfg(feature = "debug")]
                 op,
                 ..
             }) => {
@@ -1194,11 +1209,11 @@ where
                     }
 
                     if let Stmt::Block(block) = &mut bs.stmts[0] {
-                        if block
-                            .stmts
-                            .iter()
-                            .all(|stmt| !matches!(stmt, Stmt::Decl(..)))
-                        {
+                        let stmts = &block.stmts;
+                        if maybe_par!(
+                            stmts.iter().all(|stmt| !matches!(stmt, Stmt::Decl(..))),
+                            *crate::LIGHT_TASK_PARALLELS
+                        ) {
                             report_change!("optimizer: Removing nested block");
                             self.changed = true;
                             bs.stmts = block.stmts.take();
@@ -1540,7 +1555,12 @@ where
 
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
     fn visit_mut_decl(&mut self, decl: &mut Decl) {
-        decl.visit_mut_children_with(self);
+        match decl {
+            Decl::Class(class_decl) => self.visit_mut_class(&mut class_decl.class),
+            Decl::Fn(fn_decl) => self.visit_mut_fn_decl(fn_decl),
+            Decl::Var(var_decl) => self.visit_mut_var_decl(var_decl),
+            _ => decl.visit_mut_children_with(self),
+        };
 
         self.drop_unused_decl(decl);
         self.store_typeofs(decl);
@@ -1682,7 +1702,7 @@ where
         }
 
         #[cfg(feature = "trace-ast")]
-        debug!("Output: {}", dump(e, true));
+        tracing::debug!("Output: {}", dump(e, true));
     }
 
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
@@ -1770,7 +1790,8 @@ where
             }
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             n.visit_with(&mut AssertValid);
         }
     }
@@ -1903,7 +1924,8 @@ where
             if let Some(body) = n.body.as_mut() {
                 // Bypass block scope handler.
                 body.visit_mut_children_with(optimizer);
-                if cfg!(debug_assertions) {
+                #[cfg(debug_assertions)]
+                {
                     body.visit_with(&mut AssertValid);
                 }
             }
@@ -1925,7 +1947,8 @@ where
             drop_invalid_stmts(&mut body.stmts);
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             n.visit_with(&mut AssertValid);
         }
     }
@@ -2107,7 +2130,8 @@ where
             }
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             n.visit_with(&mut AssertValid);
         }
     }
@@ -2189,7 +2213,8 @@ where
         let old_prepend = self.prepend_stmts.take();
         let old_append = self.append_stmts.take();
 
-        let _tracing = if cfg!(feature = "debug") && self.debug_infinite_loop {
+        #[cfg(feature = "debug")]
+        let _tracing = if self.debug_infinite_loop {
             let text = dump(&*s, false);
 
             if text.lines().count() < 10 {
@@ -2228,7 +2253,8 @@ where
                 _ => {}
             }
 
-            if cfg!(debug_assertions) {
+            #[cfg(debug_assertions)]
+            {
                 s.visit_with(&mut AssertValid);
             }
         }
@@ -2274,7 +2300,8 @@ where
                     .collect(),
             });
 
-            if cfg!(debug_assertions) {
+            #[cfg(debug_assertions)]
+            {
                 s.visit_with(&mut AssertValid);
             }
         }
@@ -2284,7 +2311,8 @@ where
 
         let len = self.prepend_stmts.len();
 
-        if cfg!(feature = "debug") && self.debug_infinite_loop {
+        #[cfg(feature = "debug")]
+        if self.debug_infinite_loop {
             let text = dump(&*s, false);
 
             if text.lines().count() < 10 {
@@ -2343,7 +2371,8 @@ where
 
         debug_assert_eq!(self.prepend_stmts.len(), len);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             s.visit_with(&mut AssertValid);
         }
 
@@ -2369,7 +2398,8 @@ where
 
         debug_assert_eq!(self.prepend_stmts.len(), len);
 
-        if cfg!(feature = "debug") && self.debug_infinite_loop {
+        #[cfg(feature = "debug")]
+        if self.debug_infinite_loop {
             let text = dump(&*s, false);
 
             if text.lines().count() < 10 {
@@ -2379,7 +2409,8 @@ where
 
         debug_assert_eq!(self.prepend_stmts.len(), len);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             s.visit_with(&mut AssertValid);
         }
 
@@ -2388,15 +2419,18 @@ where
 
     fn visit_mut_stmts(&mut self, stmts: &mut Vec<Stmt>) {
         // Skip if `use asm` exists.
-        if stmts.iter().any(|stmt| match stmt.as_stmt() {
-            Some(Stmt::Expr(stmt)) => match &*stmt.expr {
-                Expr::Lit(Lit::Str(Str { raw, .. })) => {
-                    matches!(raw, Some(value) if value == "\"use asm\"" || value == "'use asm'")
-                }
+        if maybe_par!(
+            stmts.iter().any(|stmt| match stmt.as_stmt() {
+                Some(Stmt::Expr(stmt)) => match &*stmt.expr {
+                    Expr::Lit(Lit::Str(Str { raw, .. })) => {
+                        matches!(raw, Some(value) if value == "\"use asm\"" || value == "'use asm'")
+                    }
+                    _ => false,
+                },
                 _ => false,
-            },
-            _ => false,
-        }) {
+            }),
+            *crate::LIGHT_TASK_PARALLELS
+        ) {
             return;
         }
 
@@ -2420,7 +2454,8 @@ where
             }
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
     }
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
index 249b355c8a1..72fdeeb7e9a 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
@@ -10,16 +10,18 @@ use swc_ecma_utils::{
     StmtLike,
 };
 use swc_ecma_visit::{noop_visit_type, Visit, VisitWith};
+#[cfg(feature = "debug")]
 use tracing::{span, Level};
 
 use super::{is_pure_undefined, Optimizer};
+#[cfg(feature = "debug")]
+use crate::debug::dump;
 use crate::{
     alias::{collect_infects_from, AliasConfig},
     compress::{
         optimize::{unused::PropertyAccessOpts, util::replace_id_with_expr},
         util::{is_directive, is_ident_used_by, replace_expr},
     },
-    debug::dump,
     mode::Mode,
     option::CompressOptions,
     util::{idents_used_by, idents_used_by_ignoring_nested, ExprOptExt, ModuleItemExt},
@@ -641,7 +643,8 @@ where
 
         exprs.push(buf);
 
-        let _tracing = if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        let _tracing = {
             let buf_len = exprs.iter().map(|v| v.len()).collect::<Vec<_>>();
             Some(
                 tracing::span!(
@@ -651,8 +654,6 @@ where
                 )
                 .entered(),
             )
-        } else {
-            None
         };
 
         for mut exprs in exprs {
@@ -711,7 +712,8 @@ where
     pub(super) fn merge_sequences_in_seq_expr(&mut self, e: &mut SeqExpr) {
         self.normalize_sequences(e);
 
-        let _tracing = if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        let _tracing = {
             let e_str = dump(&*e, false);
 
             Some(
@@ -722,8 +724,6 @@ where
                 )
                 .entered(),
             )
-        } else {
-            None
         };
 
         if !self.options.sequences() && !e.span.has_mark(self.marks.synthesized_seq) {
@@ -752,13 +752,12 @@ where
     /// TODO(kdy1): Check for side effects and call merge_sequential_expr more
     /// if expressions between a and b are side-effect-free.
     fn merge_sequences_in_exprs(&mut self, exprs: &mut Vec<Mergable>) -> Result<(), ()> {
-        let _tracing = if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        let _tracing = {
             Some(
                 tracing::span!(Level::TRACE, "merge_sequences_in_exprs", len = exprs.len())
                     .entered(),
             )
-        } else {
-            None
         };
 
         for idx in 0..exprs.len() {
@@ -1207,7 +1206,8 @@ where
     ///
     /// Returns [Err] iff we should stop checking.
     fn merge_sequential_expr(&mut self, a: &mut Mergable, b: &mut Expr) -> Result<bool, ()> {
-        let _tracing = if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        let _tracing = {
             let b_str = dump(&*b, false);
             let a_id = a.id();
 
@@ -1220,8 +1220,6 @@ where
                 )
                 .entered(),
             )
-        } else {
-            None
         };
 
         match a {
@@ -1578,6 +1576,7 @@ where
             _ => {}
         }
 
+        #[cfg(feature = "debug")]
         match a {
             Mergable::Var(a) => {
                 trace_op!(
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
index 2c42dfbe44d..ee82c34e8ed 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/unused.rs
@@ -4,11 +4,12 @@ use swc_ecma_ast::*;
 use swc_ecma_utils::contains_ident_ref;
 
 use super::Optimizer;
+#[cfg(feature = "debug")]
+use crate::debug::dump;
 use crate::{
     compress::{
         optimize::util::class_has_side_effect, util::is_global_var_with_pure_property_access,
     },
-    debug::dump,
     mode::Mode,
     option::PureGetterOption,
 };
@@ -55,6 +56,7 @@ where
             }
         }
 
+        #[cfg(debug_assertions)]
         let had_init = var.init.is_some();
 
         match &mut var.init {
@@ -88,7 +90,8 @@ where
             return;
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             if let Some(VarDeclKind::Const | VarDeclKind::Let) = self.ctx.var_kind {
                 if had_init && var.init.is_none() {
                     unreachable!("const/let variable without initializer: {:#?}", var);
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/util.rs b/crates/swc_ecma_minifier/src/compress/optimize/util.rs
index 6eac9a68fa0..d2b384d6611 100644
--- a/crates/swc_ecma_minifier/src/compress/optimize/util.rs
+++ b/crates/swc_ecma_minifier/src/compress/optimize/util.rs
@@ -34,9 +34,9 @@ where
     }
 
     /// RAII guard to change context temporarically
-    #[inline]
     pub(super) fn with_ctx(&mut self, ctx: Ctx) -> WithCtx<'_, 'b, M> {
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             let scope_ctxt = ctx.scope;
             if self.ctx.scope != scope_ctxt {
                 self.data.scopes.get(&scope_ctxt).expect("scope not found");
@@ -250,7 +250,8 @@ impl VisitMut for MultiReplacer<'_> {
             items.visit_mut_children_with(self);
 
             if !self.changed {
-                if cfg!(feature = "debug") {
+                #[cfg(feature = "debug")]
+                {
                     let keys = self.vars.iter().map(|(k, _)| k.clone()).collect::<Vec<_>>();
                     debug!("Dropping {:?}", keys);
                 }
diff --git a/crates/swc_ecma_minifier/src/compress/pure/bools.rs b/crates/swc_ecma_minifier/src/compress/pure/bools.rs
index bdcdf620790..8642cfcd80d 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/bools.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/bools.rs
@@ -164,6 +164,7 @@ impl Pure<'_> {
                     let can_remove = if *op == op!("&&") { rb } else { !rb };
 
                     if can_remove {
+                        #[allow(clippy::if_same_then_else)]
                         if *op == op!("&&") {
                             report_change!("booleans: Compressing `!foo && true` as `!foo`");
                         } else {
diff --git a/crates/swc_ecma_minifier/src/compress/pure/conds.rs b/crates/swc_ecma_minifier/src/compress/pure/conds.rs
index a24368e364b..92a91d14731 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/conds.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/conds.rs
@@ -5,7 +5,9 @@ use swc_ecma_ast::*;
 use swc_ecma_utils::{ExprExt, Type, Value};
 
 use super::Pure;
-use crate::{compress::util::negate_cost, debug::dump, util::make_bool};
+#[cfg(feature = "debug")]
+use crate::debug::dump;
+use crate::{compress::util::negate_cost, util::make_bool};
 
 impl Pure<'_> {
     ///
@@ -130,6 +132,7 @@ impl Pure<'_> {
         }
 
         report_change!("conditionals: `a ? foo : bar` => `!a ? bar : foo` (considered cost)");
+        #[cfg(feature = "debug")]
         let start_str = dump(&*cond, false);
 
         self.negate(&mut cond.test, true, false);
diff --git a/crates/swc_ecma_minifier/src/compress/pure/ctx.rs b/crates/swc_ecma_minifier/src/compress/pure/ctx.rs
index 4b97c027cdd..068cca300c4 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/ctx.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/ctx.rs
@@ -29,7 +29,6 @@ pub(super) struct Ctx {
 
 impl<'b> Pure<'b> {
     /// RAII guard to change context temporarically
-    #[inline]
     pub(super) fn with_ctx(&mut self, ctx: Ctx) -> WithCtx<'_, 'b> {
         let orig_ctx = self.ctx;
         self.ctx = ctx;
diff --git a/crates/swc_ecma_minifier/src/compress/pure/dead_code.rs b/crates/swc_ecma_minifier/src/compress/pure/dead_code.rs
index 2ae492434c8..f9035893bbd 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/dead_code.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/dead_code.rs
@@ -1,10 +1,11 @@
+use rayon::prelude::*;
 use swc_common::{util::take::Take, EqIgnoreSpan, Spanned, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_utils::{extract_var_ids, ExprExt, StmtExt, StmtLike, Value};
 use swc_ecma_visit::{noop_visit_type, Visit, VisitWith};
 
 use super::Pure;
-use crate::{compress::util::is_fine_for_if_cons, util::ModuleItemExt};
+use crate::{compress::util::is_fine_for_if_cons, maybe_par, util::ModuleItemExt};
 
 /// Methods related to option `dead_code`.
 impl Pure<'_> {
@@ -229,29 +230,34 @@ impl Pure<'_> {
 
             report_change!("Dropping statements after a control keyword");
 
-            let mut new_stmts = Vec::with_capacity(stmts.len());
-            let mut decls = vec![];
-            let mut hoisted_fns = vec![];
+            let stmts_len = stmts.len();
 
             // Hoist function and `var` declarations above return.
-            stmts
-                .iter_mut()
-                .skip(idx + 1)
-                .for_each(|stmt| match stmt.take().try_into_stmt() {
-                    Ok(Stmt::Decl(Decl::Fn(f))) => {
-                        hoisted_fns.push(Stmt::Decl(Decl::Fn(f)).into());
-                    }
-                    Ok(t) => {
-                        let ids = extract_var_ids(&t).into_iter().map(|i| VarDeclarator {
-                            span: i.span,
-                            name: i.into(),
-                            init: None,
-                            definite: false,
-                        });
-                        decls.extend(ids);
-                    }
-                    Err(item) => new_stmts.push(item),
-                });
+            let (decls, hoisted_fns, mut new_stmts) = stmts.iter_mut().skip(idx + 1).fold(
+                (
+                    Vec::with_capacity(stmts_len),
+                    Vec::<T>::with_capacity(stmts_len),
+                    Vec::with_capacity(stmts_len),
+                ),
+                |(mut decls, mut hoisted_fns, mut new_stmts), stmt| {
+                    match stmt.take().try_into_stmt() {
+                        Ok(Stmt::Decl(Decl::Fn(f))) => {
+                            hoisted_fns.push(Stmt::Decl(Decl::Fn(f)).into());
+                        }
+                        Ok(t) => {
+                            let ids = extract_var_ids(&t).into_iter().map(|i| VarDeclarator {
+                                span: i.span,
+                                name: i.into(),
+                                init: None,
+                                definite: false,
+                            });
+                            decls.extend(ids);
+                        }
+                        Err(item) => new_stmts.push(item),
+                    };
+                    (decls, hoisted_fns, new_stmts)
+                },
+            );
 
             if !decls.is_empty() {
                 new_stmts.push(
@@ -380,34 +386,58 @@ impl Pure<'_> {
         T: StmtLike,
     {
         fn is_ok(b: &BlockStmt) -> bool {
-            b.stmts.iter().all(is_fine_for_if_cons)
+            maybe_par!(
+                b.stmts.iter().all(is_fine_for_if_cons),
+                *crate::LIGHT_TASK_PARALLELS
+            )
         }
 
-        if stmts
-            .iter()
-            .all(|stmt| !matches!(stmt.as_stmt(), Some(Stmt::Block(b)) if is_ok(b)))
-        {
+        if maybe_par!(
+            stmts
+                .iter()
+                .all(|stmt| !matches!(stmt.as_stmt(), Some(Stmt::Block(b)) if is_ok(b))),
+            *crate::LIGHT_TASK_PARALLELS
+        ) {
             return;
         }
 
         self.changed = true;
         report_change!("Dropping useless block");
 
-        let mut new = vec![];
-        for stmt in stmts.take() {
-            match stmt.try_into_stmt() {
-                Ok(v) => match v {
-                    Stmt::Block(v) if is_ok(&v) => {
-                        new.extend(v.stmts.into_iter().map(T::from_stmt));
-                    }
-                    _ => new.push(T::from_stmt(v)),
-                },
-                Err(v) => {
-                    new.push(v);
-                }
-            }
-        }
+        let old_stmts = stmts.take();
 
+        let new: Vec<T> = if old_stmts.len() >= *crate::LIGHT_TASK_PARALLELS {
+            old_stmts
+                .into_par_iter()
+                .flat_map(|stmt| match stmt.try_into_stmt() {
+                    Ok(v) => match v {
+                        Stmt::Block(v) if is_ok(&v) => {
+                            let stmts = v.stmts;
+                            maybe_par!(
+                                stmts.into_iter().map(T::from_stmt).collect(),
+                                *crate::LIGHT_TASK_PARALLELS
+                            )
+                        }
+                        _ => vec![T::from_stmt(v)],
+                    },
+                    Err(v) => vec![v],
+                })
+                .collect()
+        } else {
+            let mut new = Vec::with_capacity(old_stmts.len() * 2);
+            old_stmts
+                .into_iter()
+                .for_each(|stmt| match stmt.try_into_stmt() {
+                    Ok(v) => match v {
+                        Stmt::Block(v) if is_ok(&v) => {
+                            new.extend(v.stmts.into_iter().map(T::from_stmt));
+                        }
+                        _ => new.push(T::from_stmt(v)),
+                    },
+                    Err(v) => new.push(v),
+                });
+            new
+        };
         *stmts = new;
     }
 
@@ -437,20 +467,24 @@ impl Pure<'_> {
             return;
         }
 
-        if !stmts.iter().any(|stmt| match stmt.as_stmt() {
-            Some(Stmt::If(s)) => s.test.cast_to_bool(&self.expr_ctx).1.is_known(),
-            _ => false,
-        }) {
+        if !maybe_par!(
+            stmts.iter().any(|stmt| match stmt.as_stmt() {
+                Some(Stmt::If(s)) => s.test.cast_to_bool(&self.expr_ctx).1.is_known(),
+                _ => false,
+            }),
+            *crate::LIGHT_TASK_PARALLELS
+        ) {
             return;
         }
 
         self.changed = true;
         report_change!("dead_code: Removing dead codes");
 
-        let mut new = vec![];
-
-        for stmt in stmts.take() {
-            match stmt.try_into_stmt() {
+        let mut new = Vec::with_capacity(stmts.len());
+        stmts
+            .take()
+            .into_iter()
+            .for_each(|stmt| match stmt.try_into_stmt() {
                 Ok(stmt) => match stmt {
                     Stmt::If(mut s) => {
                         if let Value::Known(v) = s.test.cast_to_bool(&self.expr_ctx).1 {
@@ -462,14 +496,16 @@ impl Pure<'_> {
 
                             if v {
                                 if let Some(alt) = s.alt.take() {
-                                    var_ids.extend(alt.extract_var_ids().into_iter().map(|name| {
-                                        VarDeclarator {
+                                    var_ids = alt
+                                        .extract_var_ids()
+                                        .into_iter()
+                                        .map(|name| VarDeclarator {
                                             span: DUMMY_SP,
                                             name: Pat::Ident(name.into()),
                                             init: None,
                                             definite: Default::default(),
-                                        }
-                                    }));
+                                        })
+                                        .collect();
                                 }
                                 if !var_ids.is_empty() {
                                     new.push(T::from_stmt(Stmt::Decl(Decl::Var(VarDecl {
@@ -481,14 +517,17 @@ impl Pure<'_> {
                                 }
                                 new.push(T::from_stmt(*s.cons.take()));
                             } else {
-                                var_ids.extend(s.cons.extract_var_ids().into_iter().map(|name| {
-                                    VarDeclarator {
+                                var_ids = s
+                                    .cons
+                                    .extract_var_ids()
+                                    .into_iter()
+                                    .map(|name| VarDeclarator {
                                         span: DUMMY_SP,
                                         name: Pat::Ident(name.into()),
                                         init: None,
                                         definite: Default::default(),
-                                    }
-                                }));
+                                    })
+                                    .collect();
                                 if !var_ids.is_empty() {
                                     new.push(T::from_stmt(Stmt::Decl(Decl::Var(VarDecl {
                                         span: DUMMY_SP,
@@ -502,14 +541,13 @@ impl Pure<'_> {
                                 }
                             }
                         } else {
-                            new.push(T::from_stmt(Stmt::If(s)))
+                            new.push(T::from_stmt(Stmt::If(s)));
                         }
                     }
                     _ => new.push(T::from_stmt(stmt)),
                 },
                 Err(stmt) => new.push(stmt),
-            }
-        }
+            });
 
         *stmts = new;
     }
diff --git a/crates/swc_ecma_minifier/src/compress/pure/if_return.rs b/crates/swc_ecma_minifier/src/compress/pure/if_return.rs
index d9b75e02413..6c7f7d15824 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/if_return.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/if_return.rs
@@ -85,8 +85,8 @@ impl Pure<'_> {
             "if_return: Negating `foo` in `if (foo) return; bar()` to make it `if (!foo) bar()`"
         );
 
-        let mut new = vec![];
-        let mut fn_decls = vec![];
+        let mut new = Vec::with_capacity(stmts.len());
+        let mut fn_decls = Vec::with_capacity(stmts.len());
         new.extend(stmts.drain(..pos_of_if));
         let cons = stmts
             .drain(1..)
diff --git a/crates/swc_ecma_minifier/src/compress/pure/misc.rs b/crates/swc_ecma_minifier/src/compress/pure/misc.rs
index a916b4309ec..e1821c50428 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/misc.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/misc.rs
@@ -647,7 +647,6 @@ impl Pure<'_> {
         }))
     }
 
-    #[inline(never)]
     pub(super) fn ignore_return_value(&mut self, e: &mut Expr, opts: DropOpts) {
         self.optimize_expr_in_bool_ctx(e, true);
 
diff --git a/crates/swc_ecma_minifier/src/compress/pure/mod.rs b/crates/swc_ecma_minifier/src/compress/pure/mod.rs
index 75bafd74d8d..e804a4eac44 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/mod.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/mod.rs
@@ -5,16 +5,15 @@ use swc_common::{pass::Repeated, util::take::Take, SyntaxContext, DUMMY_SP, GLOB
 use swc_ecma_ast::*;
 use swc_ecma_utils::{undefined, ExprCtx};
 use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith, VisitWith};
+#[cfg(feature = "debug")]
 use tracing::{debug, span, Level};
 
 use self::{ctx::Ctx, misc::DropOpts};
+#[cfg(feature = "debug")]
+use crate::debug::dump;
 use crate::{
-    analyzer::ProgramData,
-    debug::{dump, AssertValid},
-    marks::Marks,
-    option::CompressOptions,
-    util::ModuleItemExt,
-    MAX_PAR_DEPTH,
+    analyzer::ProgramData, debug::AssertValid, marks::Marks, maybe_par, option::CompressOptions,
+    util::ModuleItemExt, MAX_PAR_DEPTH,
 };
 
 mod arrows;
@@ -40,6 +39,8 @@ pub(crate) struct PureOptimizerConfig {
     pub enable_join_vars: bool,
 
     pub force_str_for_tpl: bool,
+
+    #[cfg(feature = "debug")]
     pub debug_infinite_loop: bool,
 }
 
@@ -101,32 +102,37 @@ impl Pure<'_> {
     {
         self.remove_dead_branch(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.drop_unreachable_stmts(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.drop_useless_blocks(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         self.collapse_vars_without_init(stmts);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             stmts.visit_with(&mut AssertValid);
         }
 
         if self.config.enable_join_vars {
             self.join_vars(stmts);
 
-            if cfg!(debug_assertions) {
+            #[cfg(debug_assertions)]
+            {
                 stmts.visit_with(&mut AssertValid);
             }
         }
@@ -174,29 +180,50 @@ impl Pure<'_> {
                 self.changed |= v.changed;
             }
         } else {
-            GLOBALS.with(|globals| {
-                let changed = nodes
-                    .par_iter_mut()
-                    .map(|node| {
-                        GLOBALS.set(globals, || {
-                            let mut v = Pure {
-                                expr_ctx: self.expr_ctx.clone(),
-                                ctx: Ctx {
-                                    par_depth: self.ctx.par_depth + 1,
-                                    ..self.ctx
-                                },
-                                changed: false,
-                                ..*self
-                            };
-                            node.visit_mut_with(&mut v);
+            let mut changed = false;
+            if nodes.len() >= *crate::HEAVY_TASK_PARALLELS {
+                GLOBALS.with(|globals| {
+                    changed = nodes
+                        .par_iter_mut()
+                        .map(|node| {
+                            GLOBALS.set(globals, || {
+                                let mut v = Pure {
+                                    expr_ctx: self.expr_ctx.clone(),
+                                    ctx: Ctx {
+                                        par_depth: self.ctx.par_depth + 1,
+                                        ..self.ctx
+                                    },
+                                    changed: false,
+                                    ..*self
+                                };
+                                node.visit_mut_with(&mut v);
 
-                            v.changed
+                                v.changed
+                            })
                         })
-                    })
-                    .reduce(|| false, |a, b| a || b);
+                        .reduce(|| false, |a, b| a || b);
+                })
+            } else {
+                changed = nodes
+                    .iter_mut()
+                    .map(|node| {
+                        let mut v = Pure {
+                            expr_ctx: self.expr_ctx.clone(),
+                            ctx: Ctx {
+                                par_depth: self.ctx.par_depth + 1,
+                                ..self.ctx
+                            },
+                            changed: false,
+                            ..*self
+                        };
+                        node.visit_mut_with(&mut v);
 
-                self.changed |= changed;
-            });
+                        v.changed
+                    })
+                    .reduce(|a, b| a || b)
+                    .unwrap_or(false);
+            }
+            self.changed |= changed;
         }
     }
 }
@@ -217,7 +244,8 @@ impl VisitMut for Pure<'_> {
     }
 
     fn visit_mut_bin_expr(&mut self, e: &mut BinExpr) {
-        e.visit_mut_children_with(self);
+        self.visit_mut_expr(&mut e.left);
+        self.visit_mut_expr(&mut e.right);
 
         self.compress_cmp_with_long_op(e);
 
@@ -545,7 +573,8 @@ impl VisitMut for Pure<'_> {
 
         self.optimize_arrow_method_prop(p);
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             p.visit_with(&mut AssertValid);
         }
     }
@@ -570,7 +599,11 @@ impl VisitMut for Pure<'_> {
     fn visit_mut_seq_expr(&mut self, e: &mut SeqExpr) {
         e.visit_mut_children_with(self);
 
-        if e.exprs.iter().any(|e| e.is_seq()) {
+        let exprs = &e.exprs;
+        if maybe_par!(
+            exprs.iter().any(|e| e.is_seq()),
+            *crate::LIGHT_TASK_PARALLELS
+        ) {
             let mut exprs = vec![];
 
             for e in e.exprs.take() {
@@ -620,13 +653,15 @@ impl VisitMut for Pure<'_> {
 
         e.exprs.retain(|e| !e.is_invalid());
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             e.visit_with(&mut AssertValid);
         }
     }
 
     fn visit_mut_stmt(&mut self, s: &mut Stmt) {
-        let _tracing = if cfg!(feature = "debug") && self.config.debug_infinite_loop {
+        #[cfg(feature = "debug")]
+        let _tracing = if self.config.debug_infinite_loop {
             let text = dump(&*s, false);
 
             if text.lines().count() < 10 {
@@ -649,7 +684,8 @@ impl VisitMut for Pure<'_> {
             s.visit_mut_children_with(&mut *self.with_ctx(ctx));
         }
 
-        if cfg!(feature = "debug") && self.config.debug_infinite_loop {
+        #[cfg(feature = "debug")]
+        if self.config.debug_infinite_loop {
             let text = dump(&*s, false);
 
             if text.lines().count() < 10 {
@@ -683,7 +719,8 @@ impl VisitMut for Pure<'_> {
             }
         }
 
-        if cfg!(feature = "debug") && self.config.debug_infinite_loop {
+        #[cfg(feature = "debug")]
+        if self.config.debug_infinite_loop {
             let text = dump(&*s, false);
 
             if text.lines().count() < 10 {
@@ -691,7 +728,8 @@ impl VisitMut for Pure<'_> {
             }
         }
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             s.visit_with(&mut AssertValid);
         }
     }
@@ -717,7 +755,8 @@ impl VisitMut for Pure<'_> {
 
         items.retain(|s| !matches!(s, Stmt::Empty(..)));
 
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             items.visit_with(&mut AssertValid);
         }
     }
diff --git a/crates/swc_ecma_minifier/src/compress/pure/vars.rs b/crates/swc_ecma_minifier/src/compress/pure/vars.rs
index c6e1c026613..d6bf0944c22 100644
--- a/crates/swc_ecma_minifier/src/compress/pure/vars.rs
+++ b/crates/swc_ecma_minifier/src/compress/pure/vars.rs
@@ -57,14 +57,13 @@ impl Pure<'_> {
         self.changed = true;
 
         let mut cur: Option<VarDecl> = None;
-        let mut new = vec![];
 
-        for stmt in stmts.take() {
+        let mut new: Vec<T> = Vec::with_capacity(stmts.len() * 2 + 1);
+        stmts.take().into_iter().for_each(|stmt| {
             match stmt.try_into_stmt() {
                 Ok(stmt) => {
                     if is_directive(&stmt) {
-                        new.push(T::from_stmt(stmt));
-                        continue;
+                        return new.push(T::from_stmt(stmt));
                     }
 
                     match stmt {
@@ -73,11 +72,10 @@ impl Pure<'_> {
                                 v.decls.extend(var.decls);
                             }
                             _ => {
-                                new.extend(
-                                    cur.take().map(Decl::Var).map(Stmt::Decl).map(T::from_stmt),
-                                );
-
-                                cur = Some(var)
+                                if let Some(s) = cur.take().map(|c| Stmt::Decl(Decl::Var(c))) {
+                                    new.push(T::from_stmt(s));
+                                }
+                                cur = Some(var);
                             }
                         },
                         Stmt::For(mut stmt) => match &mut stmt.init {
@@ -86,22 +84,23 @@ impl Pure<'_> {
                                     kind: VarDeclKind::Var,
                                     ..
                                 },
-                            )) => match &mut cur {
-                                Some(cur) if cur.kind == var.kind => {
-                                    // Merge
-                                    cur.decls.append(&mut var.decls);
-                                    var.decls = cur.decls.take();
+                            )) => {
+                                match &mut cur {
+                                    Some(cur) if cur.kind == var.kind => {
+                                        // Merge
+                                        cur.decls.append(&mut var.decls);
+                                        var.decls = cur.decls.take();
 
-                                    new.push(T::from_stmt(Stmt::For(stmt)))
+                                        new.push(T::from_stmt(Stmt::For(stmt)));
+                                    }
+                                    _ => {
+                                        if let Some(s) = cur.take() {
+                                            new.push(T::from_stmt(Stmt::Decl(Decl::Var(s))));
+                                        }
+                                        new.push(T::from_stmt(Stmt::For(stmt)));
+                                    }
                                 }
-                                _ => {
-                                    new.extend(
-                                        cur.take().map(Decl::Var).map(Stmt::Decl).map(T::from_stmt),
-                                    );
-
-                                    new.push(T::from_stmt(Stmt::For(stmt)))
-                                }
-                            },
+                            }
                             None if cur
                                 .as_ref()
                                 .map(|v| v.kind == VarDeclKind::Var)
@@ -112,32 +111,35 @@ impl Pure<'_> {
                                     .and_then(|v| if v.decls.is_empty() { None } else { Some(v) })
                                     .map(VarDeclOrExpr::VarDecl);
 
-                                new.push(T::from_stmt(Stmt::For(stmt)))
+                                new.push(T::from_stmt(Stmt::For(stmt)));
                             }
                             _ => {
-                                new.extend(
-                                    cur.take().map(Decl::Var).map(Stmt::Decl).map(T::from_stmt),
-                                );
-
-                                new.push(T::from_stmt(Stmt::For(stmt)))
+                                if let Some(s) = cur.take() {
+                                    new.push(T::from_stmt(Stmt::Decl(Decl::Var(s))));
+                                }
+                                new.push(T::from_stmt(Stmt::For(stmt)));
                             }
                         },
                         _ => {
-                            new.extend(cur.take().map(Decl::Var).map(Stmt::Decl).map(T::from_stmt));
-
-                            new.push(T::from_stmt(stmt))
+                            if let Some(s) = cur.take() {
+                                new.push(T::from_stmt(Stmt::Decl(Decl::Var(s))));
+                            }
+                            new.push(T::from_stmt(stmt));
                         }
                     }
                 }
                 Err(item) => {
-                    new.extend(cur.take().map(Decl::Var).map(Stmt::Decl).map(T::from_stmt));
-
+                    if let Some(s) = cur.take() {
+                        new.push(T::from_stmt(Stmt::Decl(Decl::Var(s))));
+                    }
                     new.push(item);
                 }
             }
-        }
+        });
 
-        new.extend(cur.take().map(Decl::Var).map(Stmt::Decl).map(T::from_stmt));
+        if let Some(s) = cur.take() {
+            new.push(T::from_stmt(Stmt::Decl(Decl::Var(s))));
+        }
 
         drop_invalid_stmts(&mut new);
 
@@ -160,11 +162,10 @@ impl Pure<'_> {
         }
 
         {
+            let mut need_work = false;
             let mut found_vars_without_init = false;
             let mut found_other = false;
-            let mut need_work = false;
-
-            for stmt in &*stmts {
+            let if_need_work = stmts.iter().any(|stmt| {
                 match stmt.as_stmt() {
                     Some(Stmt::Decl(Decl::Var(
                         v @ VarDecl {
@@ -172,7 +173,9 @@ impl Pure<'_> {
                             ..
                         },
                     ))) => {
-                        if v.decls.iter().all(|v| v.init.is_none()) {
+                        if !(found_other && found_vars_without_init)
+                            && v.decls.iter().all(|v| v.init.is_none())
+                        {
                             if found_other {
                                 need_work = true;
                             }
@@ -198,12 +201,13 @@ impl Pure<'_> {
                         found_other = true;
                     }
                 }
-            }
+                need_work
+            });
 
             // Check for nested variable declartions.
             let mut v = VarWithOutInitCounter::default();
             stmts.visit_with(&mut v);
-            if !need_work && !v.need_work {
+            if !if_need_work && !v.need_work {
                 return;
             }
         }
@@ -372,15 +376,15 @@ impl VisitMut for VarMover {
         let has_init = d.iter().any(|v| v.init.is_some());
 
         if has_init {
-            let mut new = vec![];
+            let mut new = Vec::with_capacity(d.len());
 
-            for v in d.take() {
+            d.take().into_iter().for_each(|v| {
                 if v.init.is_some() {
                     new.push(v)
                 } else {
                     self.vars.push(v)
                 }
-            }
+            });
 
             *d = new;
         }
@@ -391,13 +395,13 @@ impl VisitMut for VarMover {
             new.append(&mut self.vars);
         }
 
-        for v in d.take() {
+        d.take().into_iter().for_each(|v| {
             if v.init.is_some() {
                 new.push(v)
             } else {
                 self.vars.push(v)
             }
-        }
+        });
 
         *d = new;
     }
diff --git a/crates/swc_ecma_minifier/src/compress/util/mod.rs b/crates/swc_ecma_minifier/src/compress/util/mod.rs
index d3a481e744e..b41303d3d0b 100644
--- a/crates/swc_ecma_minifier/src/compress/util/mod.rs
+++ b/crates/swc_ecma_minifier/src/compress/util/mod.rs
@@ -3,15 +3,19 @@ use std::f64;
 use swc_atoms::js_word;
 use swc_common::{util::take::Take, DUMMY_SP};
 use swc_ecma_ast::*;
+#[cfg(feature = "debug")]
 use swc_ecma_transforms_base::fixer::fixer;
 use swc_ecma_utils::{ExprCtx, ExprExt, IdentUsageFinder, Value};
+#[cfg(feature = "debug")]
+use swc_ecma_visit::{as_folder, FoldWith};
 use swc_ecma_visit::{
-    as_folder, noop_visit_mut_type, noop_visit_type, FoldWith, Visit, VisitMut, VisitMutWith,
-    VisitWith,
+    noop_visit_mut_type, noop_visit_type, Visit, VisitMut, VisitMutWith, VisitWith,
 };
 use unicode_id::UnicodeID;
 
-use crate::{debug::dump, util::ModuleItemExt};
+#[cfg(feature = "debug")]
+use crate::debug::dump;
+use crate::util::ModuleItemExt;
 
 #[cfg(test)]
 mod tests;
@@ -40,6 +44,7 @@ fn negate_inner(
     in_bool_ctx: bool,
     is_ret_val_ignored: bool,
 ) -> bool {
+    #[cfg(feature = "debug")]
     let start_str = dump(&*e, false);
 
     match e {
@@ -225,7 +230,8 @@ pub(crate) fn is_ok_to_negate_rhs(expr_ctx: &ExprCtx, rhs: &Expr) -> bool {
                 return true;
             }
 
-            if cfg!(feature = "debug") {
+            #[cfg(feature = "debug")]
+            {
                 tracing::warn!(
                     "unimplemented: is_ok_to_negate_rhs: `{}`",
                     dump(&*rhs, false)
@@ -239,6 +245,7 @@ pub(crate) fn is_ok_to_negate_rhs(expr_ctx: &ExprCtx, rhs: &Expr) -> bool {
 
 /// A negative value means that it's efficient to negate the expression.
 #[cfg_attr(feature = "debug", tracing::instrument(skip(e)))]
+#[allow(clippy::let_and_return)]
 pub(crate) fn negate_cost(
     expr_ctx: &ExprCtx,
     e: &Expr,
@@ -359,7 +366,8 @@ pub(crate) fn negate_cost(
         })();
 
         // Print more info while testing negate_cost
-        if cfg!(test) {
+        #[cfg(test)]
+        {
             trace_op!(
                 "negation cost of `{}` = {}",
                 dump(&e.clone().fold_with(&mut as_folder(fixer(None))), true),
diff --git a/crates/swc_ecma_minifier/src/debug.rs b/crates/swc_ecma_minifier/src/debug.rs
index 2891c013789..447d3c061dc 100644
--- a/crates/swc_ecma_minifier/src/debug.rs
+++ b/crates/swc_ecma_minifier/src/debug.rs
@@ -41,7 +41,8 @@ where
     N: swc_ecma_codegen::Node + Clone + VisitMutWith<DropSpan> + VisitMutWith<Debugger>,
 {
     if !force {
-        if !cfg!(feature = "debug") {
+        #[cfg(not(feature = "debug"))]
+        {
             return String::new();
         }
     }
@@ -71,7 +72,8 @@ where
 /// If the cargo feature `debug` is disabled or the environment variable
 /// `SWC_RUN` is not `1`, this function is noop.
 pub(crate) fn invoke(module: &Module) {
-    if cfg!(debug_assertions) {
+    #[cfg(debug_assertions)]
+    {
         module.visit_with(&mut AssertValid);
     }
 
diff --git a/crates/swc_ecma_minifier/src/eval.rs b/crates/swc_ecma_minifier/src/eval.rs
index 63845598fa2..3d090552e3c 100644
--- a/crates/swc_ecma_minifier/src/eval.rs
+++ b/crates/swc_ecma_minifier/src/eval.rs
@@ -239,6 +239,7 @@ impl Evaluator {
                 PureOptimizerConfig {
                     enable_join_vars: false,
                     force_str_for_tpl: Eval::force_str_for_tpl(),
+                    #[cfg(feature = "debug")]
                     debug_infinite_loop: false,
                 },
             ));
diff --git a/crates/swc_ecma_minifier/src/lib.rs b/crates/swc_ecma_minifier/src/lib.rs
index 5bf1204f0b8..888aeb7536e 100644
--- a/crates/swc_ecma_minifier/src/lib.rs
+++ b/crates/swc_ecma_minifier/src/lib.rs
@@ -28,6 +28,7 @@
 
 use compress::{pure_optimizer, PureOptimizerConfig};
 use mode::Mode;
+use once_cell::sync::Lazy;
 use swc_common::{comments::Comments, pass::Repeat, sync::Lrc, SourceMap, GLOBALS};
 use swc_ecma_ast::Module;
 use swc_ecma_visit::{FoldWith, VisitMutWith};
@@ -67,7 +68,10 @@ mod util;
 const DISABLE_BUGGY_PASSES: bool = true;
 const MAX_PAR_DEPTH: u8 = 3;
 
-#[inline]
+pub(crate) static CPU_COUNT: Lazy<usize> = Lazy::new(num_cpus::get);
+pub(crate) static HEAVY_TASK_PARALLELS: Lazy<usize> = Lazy::new(|| *CPU_COUNT * 8);
+pub(crate) static LIGHT_TASK_PARALLELS: Lazy<usize> = Lazy::new(|| *CPU_COUNT * 100);
+
 pub fn optimize(
     mut m: Module,
     _cm: Lrc<SourceMap>,
@@ -163,6 +167,7 @@ pub fn optimize(
             PureOptimizerConfig {
                 force_str_for_tpl: Minification::force_str_for_tpl(),
                 enable_join_vars: true,
+                #[cfg(feature = "debug")]
                 debug_infinite_loop: false,
             },
         )));
@@ -194,9 +199,6 @@ pub fn optimize(
 
     if let Some(ref mut t) = timings {
         t.section("hygiene");
-    }
-
-    if let Some(ref mut t) = timings {
         t.end_section();
     }
 
diff --git a/crates/swc_ecma_minifier/src/macros.rs b/crates/swc_ecma_minifier/src/macros.rs
index be5d07fc522..8ab7d0b5de8 100644
--- a/crates/swc_ecma_minifier/src/macros.rs
+++ b/crates/swc_ecma_minifier/src/macros.rs
@@ -1,6 +1,7 @@
 /// Used when something is modified.
 macro_rules! report_change {
     ($($tt:tt)+) => {{
+        #[cfg(feature = "debug")]
         tracing::debug!(
             kind = "change",
             $($tt)*
@@ -11,7 +12,8 @@ macro_rules! report_change {
 /// Used when a function decided to give up.
 macro_rules! log_abort {
     ($($tt:tt)+) => {{
-        if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        {
             tracing::trace!(
                 kind = "abort",
                 $($tt)*
@@ -22,7 +24,8 @@ macro_rules! log_abort {
 
 macro_rules! dump_change_detail {
     ($($tt:tt)+) => {{
-        if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        {
             tracing::trace!(
                 kind = "detail",
                 $($tt)*
@@ -33,7 +36,8 @@ macro_rules! dump_change_detail {
 
 macro_rules! trace_op {
     ($($tt:tt)+) => {{
-        if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        {
             tracing::trace!(
                 $($tt)*
             );
diff --git a/crates/swc_ecma_minifier/src/pass/global_defs.rs b/crates/swc_ecma_minifier/src/pass/global_defs.rs
index 6632c7e27e5..062ab4a8dda 100644
--- a/crates/swc_ecma_minifier/src/pass/global_defs.rs
+++ b/crates/swc_ecma_minifier/src/pass/global_defs.rs
@@ -79,7 +79,6 @@ impl VisitMut for GlobalDefs {
         n.visit_mut_children_with(self);
     }
 
-    #[inline]
     fn visit_mut_update_expr(&mut self, e: &mut UpdateExpr) {
         match &mut *e.arg {
             Expr::Ident(..) => {}
diff --git a/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/mod.rs b/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/mod.rs
index 6439ac2d1ab..0e46164cfa3 100644
--- a/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/mod.rs
+++ b/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/mod.rs
@@ -3,6 +3,7 @@ use swc_atoms::JsWord;
 use swc_common::collections::AHashMap;
 use swc_ecma_ast::*;
 use swc_ecma_visit::{noop_visit_type, Visit, VisitWith};
+#[cfg(feature = "debug")]
 use tracing::trace;
 
 use self::scope::Scope;
@@ -47,17 +48,18 @@ impl Analyzer {
     }
 
     fn add_decl(&mut self, id: Id) {
-        if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        {
             trace!("add_decl({:?})", id);
         }
         self.scope.add_decl(&id);
     }
 
     fn add_usage(&mut self, id: Id) {
-        if cfg!(feature = "debug") {
+        #[cfg(feature = "debug")]
+        {
             trace!("add_usage({:?})", id);
         }
-
         self.scope.add_usage(&id);
     }
 
diff --git a/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/scope.rs b/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/scope.rs
index 25550206fc6..b9705c53310 100644
--- a/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/scope.rs
+++ b/crates/swc_ecma_minifier/src/pass/mangle_names/analyzer/scope.rs
@@ -6,9 +6,10 @@ use rustc_hash::{FxHashMap, FxHashSet};
 use swc_atoms::{js_word, JsWord};
 use swc_common::{collections::AHashMap, util::take::Take};
 use swc_ecma_ast::Id;
+#[cfg(debug_assertions)]
 use tracing::debug;
 
-use crate::util::base54;
+use crate::{maybe_par, util::base54};
 
 #[derive(Debug, Default)]
 pub(crate) struct Scope {
@@ -128,7 +129,6 @@ impl Scope {
         }
     }
 
-    #[inline(never)]
     fn rename_one_scope(
         &self,
         to: &mut AHashMap<Id, JsWord>,
@@ -158,7 +158,8 @@ impl Scope {
                 }
 
                 if self.can_rename(&id, &sym, cloned_reverse) {
-                    if cfg!(debug_assertions) {
+                    #[cfg(debug_assertions)]
+                    {
                         debug!("mangle: `{}{:?}` -> {}", id.0, id.1, sym);
                     }
 
@@ -173,7 +174,6 @@ impl Scope {
         }
     }
 
-    #[inline(never)]
     fn can_rename(&self, id: &Id, symbol: &JsWord, reverse: &FxHashMap<JsWord, Vec<Id>>) -> bool {
         // We can optimize this
         // We only need to check the current scope and parents (ignoring `a` generated
@@ -194,6 +194,11 @@ impl Scope {
     }
 
     pub fn rename_cost(&self) -> usize {
-        self.data.queue.len() + self.children.iter().map(|v| v.rename_cost()).sum::<usize>()
+        let children = &self.children;
+        self.data.queue.len()
+            + maybe_par!(
+                children.iter().map(|v| v.rename_cost()).sum::<usize>(),
+                *crate::LIGHT_TASK_PARALLELS
+            )
     }
 }
diff --git a/crates/swc_ecma_minifier/src/pass/merge_exports.rs b/crates/swc_ecma_minifier/src/pass/merge_exports.rs
index 7fdf50927b8..6b9958083bf 100644
--- a/crates/swc_ecma_minifier/src/pass/merge_exports.rs
+++ b/crates/swc_ecma_minifier/src/pass/merge_exports.rs
@@ -2,6 +2,8 @@ use swc_common::{util::take::Take, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith};
 
+use crate::maybe_par;
+
 ///
 /// - merge exports
 pub(crate) fn merge_exports() -> impl VisitMut {
@@ -17,9 +19,12 @@ impl VisitMut for Merger {
     noop_visit_mut_type!();
 
     fn visit_mut_module_items(&mut self, stmts: &mut Vec<ModuleItem>) {
-        let was_module = stmts
-            .iter()
-            .any(|s| matches!(s, ModuleItem::ModuleDecl(..)));
+        let was_module = maybe_par!(
+            stmts
+                .iter()
+                .any(|s| matches!(s, ModuleItem::ModuleDecl(..))),
+            *crate::LIGHT_TASK_PARALLELS
+        );
 
         // Fast-path
         if !was_module {
diff --git a/crates/swc_ecma_minifier/src/pass/postcompress.rs b/crates/swc_ecma_minifier/src/pass/postcompress.rs
index 9b40179c2e7..5593aade1be 100644
--- a/crates/swc_ecma_minifier/src/pass/postcompress.rs
+++ b/crates/swc_ecma_minifier/src/pass/postcompress.rs
@@ -1,7 +1,7 @@
 use swc_ecma_ast::*;
 use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith};
 
-use crate::option::CompressOptions;
+use crate::{maybe_par, option::CompressOptions};
 
 pub fn postcompress_optimizer(options: &CompressOptions) -> impl '_ + VisitMut {
     PostcompressOptimizer {
@@ -38,9 +38,12 @@ impl VisitMut for PostcompressOptimizer<'_> {
     }
 
     fn visit_mut_module_items(&mut self, nodes: &mut Vec<ModuleItem>) {
-        self.ctx.is_module = nodes
-            .iter()
-            .any(|s| matches!(s, ModuleItem::ModuleDecl(..)));
+        self.ctx.is_module = maybe_par!(
+            nodes
+                .iter()
+                .any(|s| matches!(s, ModuleItem::ModuleDecl(..))),
+            *crate::LIGHT_TASK_PARALLELS
+        );
         self.ctx.is_top_level = true;
 
         nodes.visit_mut_children_with(self);
diff --git a/crates/swc_ecma_minifier/src/pass/precompress.rs b/crates/swc_ecma_minifier/src/pass/precompress.rs
index 3074c262434..ab27302dda4 100644
--- a/crates/swc_ecma_minifier/src/pass/precompress.rs
+++ b/crates/swc_ecma_minifier/src/pass/precompress.rs
@@ -6,6 +6,7 @@ use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith, VisitWith};
 use crate::{
     analyzer::{analyze, ProgramData, UsageAnalyzer},
     marks::Marks,
+    maybe_par,
     option::CompressOptions,
     util::ModuleItemExt,
 };
@@ -24,7 +25,7 @@ pub(crate) fn precompress_optimizer(options: &CompressOptions, marks: Marks) ->
 }
 
 #[derive(Debug)]
-struct PrecompressOptimizer<'a> {
+pub(crate) struct PrecompressOptimizer<'a> {
     options: &'a CompressOptions,
     marks: Marks,
 
@@ -50,9 +51,12 @@ impl PrecompressOptimizer<'_> {
         }
 
         if self.data.is_none() {
-            let has_decl = stmts
-                .iter()
-                .any(|stmt| matches!(stmt.as_module_decl(), Ok(..) | Err(Stmt::Decl(..))));
+            let has_decl = maybe_par!(
+                stmts
+                    .iter()
+                    .any(|stmt| matches!(stmt.as_module_decl(), Ok(..) | Err(Stmt::Decl(..)))),
+                *crate::LIGHT_TASK_PARALLELS
+            );
 
             if has_decl {
                 let data = Some(analyze(&*stmts, Some(self.marks)));
@@ -66,8 +70,7 @@ impl PrecompressOptimizer<'_> {
                 });
                 return;
             }
-
-            for stmt in stmts {
+            stmts.iter_mut().for_each(|stmt| {
                 stmt.visit_mut_with(&mut PrecompressOptimizer {
                     options: self.options,
                     marks: self.marks,
@@ -75,7 +78,7 @@ impl PrecompressOptimizer<'_> {
                     fn_decl_count: Default::default(),
                     ctx: self.ctx,
                 })
-            }
+            });
         }
     }
 }
diff --git a/crates/swc_ecma_minifier/src/util/mod.rs b/crates/swc_ecma_minifier/src/util/mod.rs
index faec857d67e..f14ae7b7628 100644
--- a/crates/swc_ecma_minifier/src/util/mod.rs
+++ b/crates/swc_ecma_minifier/src/util/mod.rs
@@ -139,7 +139,6 @@ pub(crate) trait ExprOptExt: Sized {
         }
     }
 
-    #[inline]
     fn prepend_exprs(&mut self, mut exprs: Vec<Box<Expr>>) {
         if exprs.is_empty() {
             return;
@@ -164,24 +163,20 @@ pub(crate) trait ExprOptExt: Sized {
 }
 
 impl ExprOptExt for Box<Expr> {
-    #[inline]
     fn as_expr(&self) -> &Expr {
         self
     }
 
-    #[inline]
     fn as_mut(&mut self) -> &mut Expr {
         self
     }
 }
 
 impl ExprOptExt for Expr {
-    #[inline]
     fn as_expr(&self) -> &Expr {
         self
     }
 
-    #[inline]
     fn as_mut(&mut self) -> &mut Expr {
         self
     }
@@ -279,14 +274,12 @@ pub(crate) trait IsModuleItem {
 }
 
 impl IsModuleItem for Stmt {
-    #[inline]
     fn is_module_item() -> bool {
         false
     }
 }
 
 impl IsModuleItem for ModuleItem {
-    #[inline]
     fn is_module_item() -> bool {
         true
     }
@@ -315,7 +308,6 @@ impl<V> Repeated for Optional<V>
 where
     V: Repeated,
 {
-    #[inline]
     fn changed(&self) -> bool {
         if self.enabled {
             return false;
@@ -324,7 +316,6 @@ where
         self.visitor.changed()
     }
 
-    #[inline]
     fn reset(&mut self) {
         if self.enabled {
             return;
@@ -347,7 +338,6 @@ impl<V> Fold for Optional<V>
 where
     V: Fold,
 {
-    #[inline(always)]
     fn fold_module(&mut self, module: Module) -> Module {
         if !self.enabled {
             return module;
@@ -548,9 +538,12 @@ pub(crate) fn can_end_conditionally(s: &Stmt) -> bool {
 }
 
 pub fn now() -> Option<Instant> {
-    if cfg!(target_arch = "wasm32") {
+    #[cfg(target_arch = "wasm32")]
+    {
         None
-    } else {
+    }
+    #[cfg(not(target_arch = "wasm32"))]
+    {
         Some(Instant::now())
     }
 }
@@ -592,3 +585,97 @@ impl Visit for EvalFinder {
         }
     }
 }
+
+#[macro_export(local_inner_macros)]
+#[allow(clippy::crate_in_macro_def)]
+macro_rules! maybe_par {
+  ($prefix:ident.$name:ident.iter().$operator:ident($($rest:expr)*), $threshold:expr) => {
+      if $prefix.$name.len() >= $threshold {
+          use rayon::prelude::*;
+          $prefix.$name.par_iter().$operator($($rest)*)
+      } else {
+          $prefix.$name.iter().$operator($($rest)*)
+      }
+  };
+
+  ($prefix:ident.$name:ident.into_iter().$operator:ident($($rest:expr)*), $threshold:expr) => {
+      if $prefix.$name.len() >= $threshold {
+          use rayon::prelude::*;
+          $prefix.$name.into_par_iter().$operator($($rest)*)
+      } else {
+          $prefix.$name.into_iter().$operator($($rest)*)
+      }
+  };
+
+  ($name:ident.iter().$operator:ident($($rest:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.par_iter().$operator($($rest)*)
+      } else {
+          $name.iter().$operator($($rest)*)
+      }
+  };
+
+  ($name:ident.into_iter().$operator:ident($($rest:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.into_par_iter().$operator($($rest)*)
+      } else {
+          $name.into_iter().$operator($($rest)*)
+      }
+  };
+
+  ($name:ident.iter_mut().$operator:ident($($rest:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.par_iter_mut().$operator($($rest)*)
+      } else {
+          $name.iter_mut().$operator($($rest)*)
+      }
+  };
+
+  ($name:ident.iter().$operator:ident($($rest:expr)*).$operator2:ident($($rest2:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.par_iter().$operator($($rest)*).$operator2($($rest2)*)
+      } else {
+          $name.iter().$operator($($rest)*).$operator2($($rest2)*)
+      }
+  };
+
+  ($name:ident.into_iter().$operator:ident($($rest:expr)*).$operator2:ident($($rest2:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.into_par_iter().$operator($($rest)*).$operator2($($rest2)*)
+      } else {
+          $name.into_iter().$operator($($rest)*).$operator2($($rest2)*)
+      }
+  };
+
+  ($name:ident.iter_mut().$operator:ident($($rest:expr)*).$operator2:ident($($rest2:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.par_iter_mut().$operator($($rest)*).$operator2($($rest2)*)
+      } else {
+          $name.iter_mut().$operator($($rest)*).$operator2($($rest2)*)
+      }
+  };
+
+  ($name:ident.iter().$operator:ident($($rest:expr)*).$operator2:ident::<$t:ty>($($rest2:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.par_iter().$operator($($rest)*).$operator2::<$t>($($rest2)*)
+      } else {
+          $name.iter().$operator($($rest)*).$operator2::<$t>($($rest2)*)
+      }
+  };
+
+  ($name:ident.iter().$operator:ident($($rest:expr)*).$operator2:ident($($rest2:expr)*).$operator3:ident($($rest3:expr)*), $threshold:expr) => {
+      if $name.len() >= $threshold {
+          use rayon::prelude::*;
+          $name.par_iter().$operator($($rest)*).$operator2($($rest2)*).$operator3($($rest3)*)
+      } else {
+          $name.iter().$operator($($rest)*).$operator2($($rest2)*).$operator3($($rest3)*)
+      }
+  };
+}
diff --git a/crates/swc_ecma_minifier/src/util/sort.rs b/crates/swc_ecma_minifier/src/util/sort.rs
index 11b999d3cb8..80aea6d87c7 100644
--- a/crates/swc_ecma_minifier/src/util/sort.rs
+++ b/crates/swc_ecma_minifier/src/util/sort.rs
@@ -1,30 +1,22 @@
 use std::cmp::Ordering;
 
-pub(crate) fn is_sorted_by<T, F>(mut items: impl Iterator<Item = T>, mut compare: F) -> bool
+pub(crate) fn is_sorted_by<I, T, F>(mut items: I, mut compare: F) -> bool
 where
+    I: Iterator<Item = T>,
     T: Copy,
     F: FnMut(&T, &T) -> Option<Ordering>,
 {
-    let mut last = match items.next() {
+    let last = match items.next() {
         Some(e) => e,
         None => return true,
     };
 
-    for curr in items {
-        if let Some(Ordering::Greater) | None = compare(&last, &curr) {
-            return false;
-        }
-        last = curr;
-    }
-
-    true
-}
-
-pub(crate) fn is_sorted_by_key<T, F, K>(items: impl Iterator<Item = T>, key: F) -> bool
-where
-    T: Copy,
-    F: FnMut(T) -> K,
-    K: Copy + PartialOrd,
-{
-    is_sorted_by(items.map(key), PartialOrd::partial_cmp)
+    items
+        .try_fold(last, |last, curr| {
+            if let Some(Ordering::Greater) | None = compare(&last, &curr) {
+                return Err(());
+            }
+            Ok(curr)
+        })
+        .is_ok()
 }
diff --git a/crates/swc_ecma_minifier/src/util/unit.rs b/crates/swc_ecma_minifier/src/util/unit.rs
index 3e3d93e2525..03966dce7ba 100644
--- a/crates/swc_ecma_minifier/src/util/unit.rs
+++ b/crates/swc_ecma_minifier/src/util/unit.rs
@@ -4,9 +4,13 @@ use swc_common::Mark;
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::{fixer::fixer, hygiene::hygiene};
 use swc_ecma_utils::DropSpan;
-use swc_ecma_visit::{as_folder, FoldWith, VisitMut, VisitMutWith, VisitWith};
+#[cfg(debug_assertions)]
+use swc_ecma_visit::VisitWith;
+use swc_ecma_visit::{as_folder, FoldWith, VisitMut, VisitMutWith};
 
-use crate::debug::{dump, AssertValid};
+use crate::debug::dump;
+#[cfg(debug_assertions)]
+use crate::debug::AssertValid;
 
 /// Indicates a unit of minifaction.
 pub(crate) trait CompileUnit:
@@ -19,11 +23,14 @@ pub(crate) trait CompileUnit:
     fn is_module() -> bool;
 
     fn dump(&self) -> String {
-        if !cfg!(feature = "debug") {
-            return String::new();
+        #[cfg(feature = "debug")]
+        {
+            self.force_dump()
+        }
+        #[cfg(not(feature = "debug"))]
+        {
+            String::new()
         }
-
-        self.force_dump()
     }
 
     fn force_dump(&self) -> String;
@@ -90,7 +97,8 @@ impl CompileUnit for FnExpr {
         V: VisitMut,
     {
         self.visit_mut_with(&mut *visitor);
-        if cfg!(debug_assertions) {
+        #[cfg(debug_assertions)]
+        {
             self.visit_with(&mut AssertValid);
         }
     }
diff --git a/crates/swc_ecma_utils/src/lib.rs b/crates/swc_ecma_utils/src/lib.rs
index 532022d2172..3322610ce64 100644
--- a/crates/swc_ecma_utils/src/lib.rs
+++ b/crates/swc_ecma_utils/src/lib.rs
@@ -1900,7 +1900,6 @@ pub fn opt_chain_test(
 }
 
 /// inject `branch` after directives
-#[inline(never)]
 pub fn prepend_stmt<T: StmtLike>(stmts: &mut Vec<T>, stmt: T) {
     let idx = stmts
         .iter()
diff --git a/crates/swc_ecma_visit/src/lib.rs b/crates/swc_ecma_visit/src/lib.rs
index dd675f59773..7981bbd690a 100644
--- a/crates/swc_ecma_visit/src/lib.rs
+++ b/crates/swc_ecma_visit/src/lib.rs
@@ -192,12 +192,10 @@ impl<V> Repeated for Folder<V>
 where
     V: Repeated + VisitMut,
 {
-    #[inline(always)]
     fn changed(&self) -> bool {
         self.0.changed()
     }
 
-    #[inline(always)]
     fn reset(&mut self) {
         self.0.reset();
     }
@@ -214,7 +212,6 @@ where
 
 macro_rules! delegate {
     ($name:ident, $T:ty) => {
-        #[inline(always)]
         fn $name(&mut self, n: &mut $T) {
             n.visit_mut_with(&mut self.0);
         }
@@ -249,7 +246,6 @@ where
 
 macro_rules! method {
     ($name:ident, $T:ty) => {
-        #[inline(always)]
         fn $name(&mut self, mut n: $T) -> $T {
             n.visit_mut_with(&mut self.0);
             n
@@ -295,7 +291,6 @@ where
 #[macro_export]
 macro_rules! noop_fold_type {
     ($name:ident, $N:tt) => {
-        #[inline]
         fn $name(&mut self, node: $crate::swc_ecma_ast::$N) -> $crate::swc_ecma_ast::$N {
             node
         }
@@ -372,7 +367,6 @@ macro_rules! noop_fold_type {
 #[macro_export]
 macro_rules! noop_visit_type {
     ($name:ident, $N:tt) => {
-        #[inline]
         fn $name(&mut self, _: &$crate::swc_ecma_ast::$N) {}
     };
     () => {
@@ -434,7 +428,6 @@ macro_rules! noop_visit_type {
 #[macro_export]
 macro_rules! noop_visit_mut_type {
     ($name:ident, $N:ident) => {
-        #[inline]
         fn $name(&mut self, _: &mut $crate::swc_ecma_ast::$N) {}
     };
     () => {
diff --git a/crates/swc_node_base/Cargo.toml b/crates/swc_node_base/Cargo.toml
index 8dd68b8ddac..34558ef56c3 100644
--- a/crates/swc_node_base/Cargo.toml
+++ b/crates/swc_node_base/Cargo.toml
@@ -14,7 +14,7 @@ bench = false
 [dependencies]
 
 [target.'cfg(not(target_os = "linux"))'.dependencies]
-mimalloc-rust = { version = "0.1" }
+mimalloc-rust = { version = "0.2" }
 
-[target.'cfg(all(target_os = "linux", target_env = "gnu", any(target_arch = "x86_64", target_arch = "aarch64")))'.dependencies]
-tikv-jemallocator = { version = "0.4", features = ["disable_initial_exec_tls"] }
+[target.'cfg(all(target_os = "linux", not(all(target_env = "musl", target_arch = "aarch64"))))'.dependencies]
+mimalloc-rust = { version = "0.2", features = ["local-dynamic-tls"] }
diff --git a/crates/swc_node_base/src/lib.rs b/crates/swc_node_base/src/lib.rs
index f853ce8a5c1..45b8321ba0d 100644
--- a/crates/swc_node_base/src/lib.rs
+++ b/crates/swc_node_base/src/lib.rs
@@ -2,14 +2,9 @@
 //!
 //! The swc crates related to the  node binding should depend on this crate.
 
-#[cfg(not(target_os = "linux"))]
-#[global_allocator]
-static GLOBAL: mimalloc_rust::GlobalMiMalloc = mimalloc_rust::GlobalMiMalloc;
-
 #[cfg(all(
-    target_os = "linux",
-    target_env = "gnu",
-    any(target_arch = "x86_64", target_arch = "aarch64")
+    not(all(target_os = "linux", target_env = "musl", target_arch = "aarch64")),
+    not(debug_assertions)
 ))]
 #[global_allocator]
-static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+static ALLOC: mimalloc_rust::GlobalMiMalloc = mimalloc_rust::GlobalMiMalloc;