Repository: vercel/next.js
Pull request: perf: memorize exclude function in webpack config

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During JavaScript profiling, I identified repeated calls to the exclude function in the webpack configuration and implemented caching to optimize it.

<img width="2248" height="772" alt="image" src="https://github.com/user-attachments/assets/1fdb03f3-2904-4195-a538-7b1f4646f0f2" />

I tested the performance using the [chakra-ui-docs](https://github.com/SyMind/chakra-ui-docs) repository with the following steps:
  1. Execute `pnpm run dev`
  2. Wait for the server to be ready (indicated by the 'Ready' message)
  3. Run `curl` on the root endpoint (`/`)

| | Webpack | Rspack |
|-|-|-|
|After| Compiled / in 8.3s (2682 modules) | Compiled / in 2.3s (2650 modules) |
|Before| Compiled / in 7.8s (2682 modules) | Compiled / in 1983ms (2650 modules) |

Changed files:
filename: packages/next/src/build/webpack-config.ts
patch: @@ -445,6 +445,22 @@ export default async function getBaseWebpackConfig(
     loggedIgnoredCompilerOptions = true
   }
 
+  const excludeCache: Record<string, boolean> = {}
+  function exclude(excludePath: string): boolean {
+    const cached = excludeCache[excludePath]
+    if (cached !== undefined) {
+      return cached
+    }
+
+    const shouldExclude =
+      excludePath.includes('node_modules') &&
+      !babelIncludeRegexes.some((r) => r.test(excludePath)) &&
+      !isResourceInPackages(excludePath, finalTranspilePackages)
+
+    excludeCache[excludePath] = shouldExclude
+    return shouldExclude
+  }
+
   const shouldIncludeExternalDirs =
     config.experimental.externalDir || !!config.transpilePackages
   const codeCondition = {
@@ -453,19 +469,7 @@ export default async function getBaseWebpackConfig(
       ? // Allowing importing TS/TSX files from outside of the root dir.
         {}
       : { include: [dir, ...babelIncludeRegexes] }),
-    exclude: (excludePath: string) => {
-      if (babelIncludeRegexes.some((r) => r.test(excludePath))) {
-        return false
-      }
-
-      const shouldBeBundled = isResourceInPackages(
-        excludePath,
-        finalTranspilePackages
-      )
-      if (shouldBeBundled) return false
-
-      return excludePath.includes('node_modules')
-    },
+    exclude,
   }
 
   const babelLoader = getBabelLoader(