Cloudflare ports TypeScript to Rust and claims 8x speed with 70% less memory

What Cloudflare built

tsrs is an experimental Rust port of the TypeScript compiler, built with VoidZero and Max Schwenk of Owner.com, incubated in Oxc, in collaboration with the TypeScript team. The pitch: faster type checks, and Rust compiles to WebAssembly without bundling a garbage collector, unlike Go, which suits browsers and Workers. Install with npm install tsrs.

Diagnostics output order differs from upstream, and Cloudflare plans to merge with tsc-rs. Maintenance will mirror its Vinext approach: agents review upstream changes, run test suites and propose fixes. Benchmarks are Cloudflare's own.

The TypeScript team says the speed is not all Rust

A TypeScript program manager on the team that owns the compiler said the 8x headline hides where the gains came from:

"a lot of the speed does not just come down to language choice, and some of what is going to make TS 7.1 faster and leaner… actually comes from optimizations discovered in tsrs."

An outside check came from a commenter who benchmarked tsgo, ts-rust, tsrs and bun on their monorepo: tsrs "is very memory efficient when bumping up the number of threads", and unlike bun it has incremental checks. The soundness question is sharper. A commenter who read the project's porting notes objected to the arena design:

"It's unsound, the LLM/human is doing the proving. They've hidden unsafe in an abstraction without removing the unsafeness."

If you run tsc in CI, the near-term gain is probably TypeScript 7.1 rather than switching to an experimental, agent-maintained port whose memory model is disputed.