Yelp Cuts Build Times 52% by Migrating from Webpack to Rspack

Yelp's engineering team published a detailed case study on their Webpack-to-Rspack migration, reporting a 52% average reduction in build times across their monorepo. The approach was notable for being methodical rather than heroic: a staged rollout that let individual teams opt in, verify their pages independently, and then switch by default once confidence was established.

The key enabler was Rspack's near-total Webpack configuration compatibility. Yelp estimated they reused roughly 95% of their existing Webpack config. That is the differentiator between Rspack and alternatives like Vite or Turbopack for large existing codebases, you are not rewriting your build system from scratch. You are swapping the engine under it.

After the migration, the team chased further gains. Converting barrel file star re-exports to named exports shaved off substantial build time. Switching import-then-reexport patterns to true re-exports saved another 30 seconds. The biggest incremental win came from Rspack's portable cache: Webpack's cache could not be shared across CI runs reliably, but Rspack's could, delivering up to 80% reduction in subsequent warm builds.

For teams sitting on large Webpack codebases and watching Vite's momentum, Yelp's experience makes the case that the middle path exists. You can get most of the Rust-bundler speed without the greenfield rewrite. Rspack 2.0, released in April, added experimental React Server Components support, closing another gap for Next.js-adjacent projects.