Migrate Performance Options

Migrate performance options for @rsbuild/core@2

@rsbuild/core@2 removed two performance options and deprecated a third. rsbuild v2 does not hard-error on the stale keys — it warns and ignores the removed ones, and the deprecated one still works — so the changes here are about adopting the replacements rather than fixing a broken build. None have a drop-in key rename, so this ships as an AI-assisted instruction.

This only affects projects whose rsbuild.config.{ts,js,mjs,cjs} sets one of the options below. If none of your configs use them, there is nothing to do.

performance.bundleAnalyze was removed

rsbuild v1 bundled webpack-bundle-analyzer and exposed it through performance.bundleAnalyze. v2 removed it to cut install size.

For every config that sets performance.bundleAnalyze, remove that option and pick one replacement:

• Preferred — Rsdoctor. Add the Rsdoctor plugin; it covers bundle-size analysis and more. See rsbuild.rs/guide/debug/rsdoctor.

• Keep webpack-bundle-analyzer. Install it and register it via tools.rspack:

  tsCopy

  import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer';
  
  export default {
    tools: {
      rspack: {
        plugins: [new BundleAnalyzerPlugin({ analyzerMode: 'static' })],
      },
    },
  };
  

If performance is left empty after removing the option, delete the empty performance: {} block too.

performance.profile was removed

performance.profile emitted an rspack stats JSON file. v2 removed it; emit the file from a small custom plugin instead.

For every config that sets performance.profile: true, remove that option and add:

import { writeFileSync } from 'node:fs';
import { join } from 'node:path';

const statsJsonPlugin = {
  name: 'stats-json-plugin',
  setup(api) {
    api.onAfterBuild(({ stats }) => {
      writeFileSync(
        join(api.context.distPath, 'stats.json'),
        JSON.stringify(stats?.toJson({}), null, 2)
      );
    });
  },
};

export default {
  plugins: [statsJsonPlugin],
};

performance.chunkSplit is deprecated

performance.chunkSplit still works in v2 but is deprecated. Migrate it to the new top-level splitChunks option, which aligns with Rspack's optimization.splitChunks.

For every config that sets performance.chunkSplit, translate strategy:

Then translate the remaining chunkSplit keys:

• override → spread its contents directly into the top-level splitChunks.

• forceSplitting → splitChunks.cacheGroups. Each forceSplitting entry name: <RegExp> expands to a full cache group:

  tsCopy

  cacheGroups: {
    <name>: {
      test: <RegExp>,
      name: '<name>',
      chunks: 'all',
      // priority 0 normally; use 1 when the `single-vendor` preset is set
      priority: 0,
      enforce: true,
    },
  }
  

forceSplitting example

export default {
-  performance: {
-    chunkSplit: {
-      forceSplitting: {
-        axios: /node_modules[\\/]axios/,
-      },
-    },
-  },
+  splitChunks: {
+    cacheGroups: {
+      axios: {
+        test: /node_modules[\\/]axios/,
+        name: 'axios',
+        chunks: 'all',
+        priority: 0,
+        enforce: true,
+      },
+    },
+  },
};

If performance is empty after removing chunkSplit, delete the empty performance: {} block.

Sample Code Changes

Before

export default defineConfig({
  performance: {
    bundleAnalyze: {},
    profile: true,
  },
});

After

import { writeFileSync } from 'node:fs';
import { join } from 'node:path';
import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer';

const statsJsonPlugin = {
  name: 'stats-json-plugin',
  setup(api) {
    api.onAfterBuild(({ stats }) => {
      writeFileSync(
        join(api.context.distPath, 'stats.json'),
        JSON.stringify(stats?.toJson({}), null, 2)
      );
    });
  },
};

export default defineConfig({
  plugins: [statsJsonPlugin],
  tools: {
    rspack: {
      plugins: [new BundleAnalyzerPlugin({ analyzerMode: 'static' })],
    },
  },
});

Reference

• @rsbuild/core v1 → v2 upgrade guide — Remove performance.bundleAnalyze
• @rsbuild/core v1 → v2 upgrade guide — Remove performance.profile
• @rsbuild/core v1 → v2 upgrade guide — Migrate performance.chunkSplit