We rewrote our Rust WASM parser in TypeScript and it got faster

Swapping Rust/WASM for TypeScript in an LLM DSL parser eliminated serialization-deserialization overhead at the JS↔WASM boundary, exposing that infrastructure latency—not language choice—dominated streaming LLM chunk processing.

Saturday, March 21, 2026 12:00 PM UTC2 MIN READSOURCE: Hacker NewsBY sys://pipeline

A team replaced their Rust/WASM parser with a TypeScript implementation and saw a performance improvement — not because Rust is slow, but because the JS↔WASM boundary overhead (string copies, serialization, deserialization) dominated latency on every streaming LLM chunk. The parser converts a custom LLM-emitted DSL into a React component tree across six stages, making boundary costs significant at streaming frequencies. A concrete, counterintuitive lesson in where real bottlenecks hide when integrating WASM into LLM streaming pipelines.