From 10f6b6bb093e585eeec25458b35d0818f82494ab Mon Sep 17 00:00:00 2001
From: Adam Turner <9087854+aa-turner@users.noreply.github.com>
Date: Sat, 19 Oct 2024 21:37:38 +0100
Subject: [PATCH] Cache the result of ``_file_checksum()``

---
 sphinx/builders/html/_assets.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/sphinx/builders/html/_assets.py b/sphinx/builders/html/_assets.py
index b2b3b9c2b..85e5e2dc2 100644
--- a/sphinx/builders/html/_assets.py
+++ b/sphinx/builders/html/_assets.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 import os
 import warnings
 import zlib
+from functools import cache
 from typing import TYPE_CHECKING, Any, NoReturn
 
 from sphinx.deprecation import RemovedInSphinx90Warning
@@ -172,9 +173,14 @@ def _file_checksum(outdir: Path, filename: str | os.PathLike[str]) -> str:
     if '?' in filename:
         msg = f'Local asset file paths must not contain query strings: {filename!r}'
         raise ThemeError(msg)
+    return _file_checksum_inner(outdir.joinpath(filename).resolve())
+
+
+@cache
+def _file_checksum_inner(file: Path) -> str:
     try:
         # Remove all carriage returns to avoid checksum differences
-        content = outdir.joinpath(filename).read_bytes().translate(None, b'\r')
+        content = file.read_bytes().translate(None, b'\r')
     except FileNotFoundError:
         return ''
     if not content: