diff --git a/wezterm-gui/src/shapecache.rs b/wezterm-gui/src/shapecache.rs
index b1a0b3d69..d62c87c41 100644
--- a/wezterm-gui/src/shapecache.rs
+++ b/wezterm-gui/src/shapecache.rs
@@ -50,7 +50,7 @@ where
         infos: &[GlyphInfo],
         glyphs: &[Rc<CachedGlyph<T>>],
     ) -> Vec<ShapedInfo<T>> {
-        let mut pos: Vec<Option<ShapedInfo<T>>> = vec![];
+        let mut pos: Vec<Option<ShapedInfo<T>>> = Vec::with_capacity(infos.len());
         let mut x = 0.;
         let mut prior_info: Option<&GlyphInfo> = None;
 
diff --git a/wezterm-gui/src/termwindow/render.rs b/wezterm-gui/src/termwindow/render.rs
index ab65fbb5a..a59aee423 100644
--- a/wezterm-gui/src/termwindow/render.rs
+++ b/wezterm-gui/src/termwindow/render.rs
@@ -1275,7 +1275,7 @@ impl super::TermWindow {
         glyph_cache: &mut GlyphCache<SrgbTexture2d>,
         infos: &[GlyphInfo],
     ) -> anyhow::Result<Vec<Rc<CachedGlyph<SrgbTexture2d>>>> {
-        let mut glyphs = vec![];
+        let mut glyphs = Vec::with_capacity(infos.len());
         for info in infos {
             let cell_idx = cluster.byte_to_cell_idx[info.cluster as usize];
             let followed_by_space = match line.cells().get(cell_idx + 1) {