“The new implementation of the virtual terminal interpreter in Rust (compiled to WASM) does it 50x faster.”
The old asciinema player was ClojureScript, and its immutable data structures churned out garbage on every frame of a heavy recording. The rewrite moved the terminal emulator to Rust in WebAssembly and the UI to SolidJS. The bundle shrank four times. The author loves Clojure and still had to leave it to make the player smooth.