System Info

rsbuild: v1.0.1-beta.3

Details

Module federation plugin seems to make the build a lot slower. HMR in particular becomes unusable.

I have a large internal rsbuild project where we can clearly see the issue. I am not sure exactly what to share as making a reproducer is quite challenging.

Maybe you have some ideas of what could impact the build time so much.

The project is using

• React plugin
• less plugin (seems that this plugin has the most impact on the rsdoctor output)
• It has ~ 20 entries

With the built-in module-federation options, the dev output takes 31.6 s instead of `13.5 s.

What I have noticed is that that once I enable the module federation plugin, a lot of time is spent on sealing chunk optimization (I don't even have time to read that text when module federation is not enabled).

• Additionally, if I only build a single entry (the largest we have), it takes about the same time to produce the output: 12s (with MF) vs 10s.
• The HMR time is also impacted by the number of entries and module federation:
  • base (single entries): ~ 1.5s
  • base (all entries): ~ 2.5s
  • with MF (single entry): ~3.25s
  • with MF (all entries): ~ 25s 💥

If I use @module-federation/enhanced, the build time increases even more (even with dts: false).

I tried to reproduce by cloning https://github.com/rspack-contrib/performance-compare/blob/main/rsbuild.config.mjs and updating the configuration as follows

export default defineConfig({
  plugins: [pluginReact()],
  source: {
    entry: Object.fromEntries(
        Array.from({ length: 200 }, (_, i) => [`index${i}`, "./src/index.tsx"])
    )
  },
  moduleFederation: {
    options: {
      name: "app",
      shared: ["react", "react-dom"]
    }
  }
});

however, it does not seem that the number of entries affects rspack and module federation so much. Also tried adding some less files and used the less-plugin, did not make a difference.

Reproduce Steps

Will share if I manage to make a small example. For now, see the description of the issue.

Is there a large project that I could fork to reproduce the issue? The example projects are small, so it might hard to notice