From 01dc72922b5c9d5a67f853d629e552886c246f33 Mon Sep 17 00:00:00 2001
From: Arsh <69170106+lilnasy@users.noreply.github.com>
Date: Fri, 19 Dec 2025 06:42:57 +0530
Subject: [PATCH] perf(oxc_parser): preallocate `tokens` vector

---
 crates/oxc_parser/src/lexer/mod.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/crates/oxc_parser/src/lexer/mod.rs b/crates/oxc_parser/src/lexer/mod.rs
index 6887ec8afd0a6..fc3b31f0a1ade 100644
--- a/crates/oxc_parser/src/lexer/mod.rs
+++ b/crates/oxc_parser/src/lexer/mod.rs
@@ -122,7 +122,11 @@ impl<'a> Lexer<'a> {
             escaped_strings: FxHashMap::default(),
             escaped_templates: FxHashMap::default(),
             multi_line_comment_end_finder: None,
-            tokens: if collect_tokens { Some(ArenaVec::new_in(allocator)) } else { None },
+            tokens: if collect_tokens {
+                Some(ArenaVec::with_capacity_in(source_text.len(), allocator))
+            } else {
+                None
+            },
         }
     }