diff --git a/semantic-tags/bench/Main.hs b/semantic-tags/bench/Main.hs
new file mode 100644
index 000000000..eb4f1d20d
--- /dev/null
+++ b/semantic-tags/bench/Main.hs
@@ -0,0 +1,33 @@
+module Main (main) where
+
+import Tags.Tagging.Precise
+import qualified Data.ByteString as B
+import Gauge
+import Source.Loc (Loc (..))
+import Source.Range
+import Source.Source as Source
+import Source.Span (Pos (..), Span (..))
+import Data.Char (ord)
+
+main :: IO ()
+main = do
+  bytes <- fmap fromUTF8 $ B.readFile "/Users/tclem/github/github/app/models/user.rb"
+  -- bytes <- fmap fromUTF8 $ B.readFile "/Users/tclem/Downloads/jquery-3.5.1.min.js"
+  -- let lineIndexes = B.elemIndices (toEnum (ord '\n')) (Source.bytes bytes)
+  defaultMain
+    [ baselineCalculateLine bytes
+    , calculateLinePRVersion bytes
+    , calculateLineWithMap bytes
+    ]
+
+baselineCalculateLine :: Source -> Benchmark
+baselineCalculateLine bytes = bench "baseline calculateLineAndSpans" $ do
+  nf (baselineCalculateLineAndSpans bytes) (Loc (Range 73754 73757) (Span (Pos 1 73669) (Pos 1 73672)))
+
+calculateLinePRVersion :: Source -> Benchmark
+calculateLinePRVersion bytes = bench "calculateLineAndSpansPRVersion " $ do
+  nf (calculateLineAndSpansPRVersion bytes) (Loc (Range 73754 73757) (Span (Pos 1 73669) (Pos 1 73672)))
+
+calculateLineWithMap :: Source -> Benchmark
+calculateLineWithMap src = bench "calculateLineAndSpansWithIndexes" $ do
+  nf (calculateLineAndSpans src (LineIndices mempty)) (Loc (Range 73754 73757) (Span (Pos 1 73669) (Pos 1 73672)))
diff --git a/semantic-tags/semantic-tags.cabal b/semantic-tags/semantic-tags.cabal
index 4ad5f1cbd..a1d8358be 100644
--- a/semantic-tags/semantic-tags.cabal
+++ b/semantic-tags/semantic-tags.cabal
@@ -48,6 +48,8 @@ library
     , semantic-source    ^>= 0.1.0
     , semantic-proto     ^>= 0
     , text               ^>= 1.2.3.1
+    , containers
+    , deepseq
   hs-source-dirs:      src
 
 test-suite test
@@ -64,3 +66,15 @@ test-suite test
     , tasty-hedgehog  ^>= 1.0.0.1
     , tasty-hunit      >= 0.10 && <1
     , text
+
+benchmark benchmarks
+  import:              haskell
+  hs-source-dirs:      bench
+  type:                exitcode-stdio-1.0
+  main-is:             Main.hs
+  ghc-options:         -threaded -static -rtsopts
+  build-depends:       base
+                     , bytestring         ^>= 0.10.8.2
+                     , semantic-tags
+                     , semantic-source
+                     , gauge ^>= 0.2.5