How uv got so fast

I love uv, the latest python dependencies manager, and use it whenever I can.

The best part about uv is its speed when compared to pip. And I’ve always assumed that its speed came from being written in Rust.

Well, TIL from Andrew Nesbitt that there are many factors into this performance, and being written in Rust is just one of them.

uv installs packages faster than pip by an order of magnitude. The usual explanation is “it’s written in Rust.” That’s true, but it doesn’t explain much. Plenty of tools are written in Rust without being notably fast. The interesting question is what design decisions made the difference … standards that enable fast paths, things uv drops that pip supports, and optimizations that don’t require Rust at all.

Speed comes from elimination. Every code path you don’t have is a code path you don’t wait for. uv’s compatibility documentation is a list of things it doesn’t do.

[And] several key optimizations could be implemented in pip today. It doesn’t, largely because backwards compatibility with fifteen years of edge cases takes precedence.