Bun adds Rust-powered React Compiler, promises 19x faster builds

Bun is putting a Rust implementation of React Compiler directly into `bun build react-compiler`, and the headline is hard to miss: on large React codebases, it is claiming 19x faster builds than the Babel plugin. That is not a tiny tooling polish pass, it is the kind of speedup that changes whether teams leave compiler passes on by default or treat them like a luxury.

React Compiler itself is a build-time tool from the React team that automatically memoizes components and hooks, which means less hand-written `useMemo`, `useCallback`, and `React.memo`. React’s own docs say it works best with React 19, while still supporting React 17 and 18, and they also make a key pipeline point clear: the compiler has to run first so it sees the original source before other JSX-rewriting transforms get involved. That ordering matters, because once another plugin has already changed the code shape, the compiler loses the clean input it needs.

The timing also fits a bigger shift in the React stack. The React team has said React Compiler is stable and production-ready, and its history traces back to Prepack in 2017 before later rewrites brought it to the current form. React’s guidance has also widened around adoption, with incremental rollout advice, an ESLint plugin, and case studies such as Sanity Studio and Wakelet showing where the compiler’s automatic memoization pays off in real apps.

Bun is not the only runtime or toolchain moving in this direction. Oxc documents experimental React Compiler support in Rust as well, and it says it vendors the Rust port rather than the Babel-based `babel-plugin-react-compiler`. Oxc also runs the compiler before its own JSX transform, matching React’s requirement that the compiler see the source first. That makes the Rust path look less like a one-off experiment and more like a shared direction across modern frontend tooling.

The Bun issue history adds another detail that developers will recognize immediately: React Compiler changes how people write React, not just how they build it. That matters because a compiler that trims build time and nudges code away from repetitive memoization patterns can alter day-to-day habits, not just CI numbers. With Bun’s PR list showing `#32504` for React Compiler integration and Bun shipping canary builds on every commit to main, the Rust version looks close enough to land in real workflows, not just slide decks.