Claude Code 偷偷换上了用 Rust 重写的 Bun，启动快了 10%，而且几乎没人发现，这才是扎实的工程优化。
Anthropic 的 Claude Code 从 v2.1.181（6月17日发布）起使用用 Rust 重写的 Bun。相比原版 Bun，Linux 启动速度提升 10%。作者通过检查二进制文件，发现内置的 Bun 版本为 v1.4.0（尚未公开发布）以及 563 个 Rust 源文件路径。该变更已部署到数百万设备上。Jarred Sumner 表示，这次升级几乎没有用户察觉。
Claude Code uses Bun written in Rust now
In Rewriting Bun in Rust Jarred Sumner made the following claim: Claude Code v2.1.181 (released June 17th) and later use the Rust port of Bun. Startup got 10% faster on Linux but otherwise, barely anyone noticed. Boring is good. I decided to have a poke at my own Claude Code installation to see if I could find evidence that it was using Bun written in Rust. I found these two commands convincing: strings ~/.local/bin/claude | grep -m1 'Bun v1' For me this outputs Bun v1.4.0 (macOS arm64) . The most recent release of Bun on GitHub is currently v1.3.14 from May 12th, so that v1.4.0 version number in Claude supports them shipping a preview of a not-yet-released Bun version. strings ~/.local/bin/claude | grep -Eo 'src/[[:alnum:]_./-]+\.rs' This outputs a list of 563 filenames , starting with these: src/runtime/bake/dev_server/mod.rs src/runtime/bake/production.rs src/bundler/bundle_v2.rs It looks like Bun in Rust is indeed being run in production across millions of different devices. Like Jarred said, "Boring is good". Tags: bun , rust , anthropic , claude-code