diff --git a/src/core/file/filePathSort.ts b/src/core/file/filePathSort.ts
index 808055d1b..2d6b4c3ed 100644
--- a/src/core/file/filePathSort.ts
+++ b/src/core/file/filePathSort.ts
@@ -1,10 +1,14 @@
 import path from 'node:path';
 
 // Sort paths for general use (not affected by git change count)
+// Uses decorate-sort-undecorate to pre-compute path.split() once per path
+// instead of O(N log N) repeated splits during comparisons
 export const sortPaths = (filePaths: string[]): string[] => {
-  return filePaths.sort((a, b) => {
-    const partsA = a.split(path.sep);
-    const partsB = b.split(path.sep);
+  const decorated = filePaths.map((p) => ({ original: p, parts: p.split(path.sep) }));
+
+  decorated.sort((a, b) => {
+    const partsA = a.parts;
+    const partsB = b.parts;
 
     for (let i = 0; i < Math.min(partsA.length, partsB.length); i++) {
       if (partsA[i] !== partsB[i]) {
@@ -21,4 +25,6 @@ export const sortPaths = (filePaths: string[]): string[] => {
     // Sort by path length when all parts are equal
     return partsA.length - partsB.length;
   });
+
+  return decorated.map((d) => d.original);
 };
diff --git a/tests/core/file/fileSearch.test.ts b/tests/core/file/fileSearch.test.ts
index 8e3e123bf..3a6e19828 100644
--- a/tests/core/file/fileSearch.test.ts
+++ b/tests/core/file/fileSearch.test.ts
@@ -531,19 +531,25 @@ node_modules
         },
       });
 
+      const sep = path.sep;
       const mockFileStructure = [
-        'root/file1.js',
-        'root/another/file3.js',
-        'root/subdir/file2.js',
-        'root/subdir/ignored.js',
+        `root${sep}file1.js`,
+        `root${sep}another${sep}file3.js`,
+        `root${sep}subdir${sep}file2.js`,
+        `root${sep}subdir${sep}ignored.js`,
       ];
 
       vi.mocked(globby).mockResolvedValue(mockFileStructure);
 
       const result = await searchFiles('/mock/root', mockConfig);
 
-      expect(result.filePaths).toEqual(mockFileStructure);
-      expect(result.filePaths).toContain('root/subdir/ignored.js');
+      expect(result.filePaths).toEqual([
+        `root${sep}another${sep}file3.js`,
+        `root${sep}subdir${sep}file2.js`,
+        `root${sep}subdir${sep}ignored.js`,
+        `root${sep}file1.js`,
+      ]);
+      expect(result.filePaths).toContain(`root${sep}subdir${sep}ignored.js`);
       expect(result.emptyDirPaths).toEqual([]);
     });