I know Gemini CLI was written in JS + React. Even the public version had a very slow startup time that some might blame on the stack. But Claude CLI is a similar stack and starts instantly, so idk, does Bun really make the difference?

Internally I didn't like Gemini CLI just because it didn't have the right skills/whatever preinstalled, so it always did stuff that made sense elsewhere but not at Google, like trying to grep through the entire monorepo. Jetski just worked.