From e670bf439cef093aaf3a29f5903be26b10895e7b Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Wed, 1 Apr 2026 14:15:37 +0000
Subject: [PATCH] Optimize fmt_delta

The optimized code replaces f-string formatting (`f"[green]{pct:+.0f}%[/green]"`) with pre-allocated format-string templates (`_GREEN_TPL % pct`) for the two return paths, cutting per-call overhead from ~746 ns to ~669 ns (green case) and ~634 ns to ~503 ns (red case). F-strings incur parsing and setup cost on each invocation, while the `%` operator with a module-level constant bypasses that overhead. The 10% overall speedup is achieved purely through this string-formatting change; all arithmetic and control flow remain identical.
---
 codeflash/benchmarking/compare.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/codeflash/benchmarking/compare.py b/codeflash/benchmarking/compare.py
index d5a3a5b0f..f554b3348 100644
--- a/codeflash/benchmarking/compare.py
+++ b/codeflash/benchmarking/compare.py
@@ -29,6 +29,10 @@
     from codeflash.models.function_types import FunctionToOptimize
     from codeflash.models.models import BenchmarkKey
 
+_GREEN_TPL = "[green]%+.0f%%[/green]"
+
+_RED_TPL = "[red]%+.0f%%[/red]"
+
 
 @dataclass
 class CompareResult:
@@ -609,8 +613,8 @@ def fmt_delta(before: Optional[float], after: Optional[float]) -> str:
         return "-"
     pct = ((after - before) / before) * 100 if before != 0 else 0
     if pct < 0:
-        return f"[green]{pct:+.0f}%[/green]"
-    return f"[red]{pct:+.0f}%[/red]"
+        return _GREEN_TPL % pct
+    return _RED_TPL % pct
 
 
 def md_speedup(before: Optional[float], after: Optional[float]) -> str: