Comment by saghm

I don't find that to be a particularly strong argument that a Python package manager would be possible to be in the same ballpark of performance as a Rust one. There's quite a lot of it that either doesn't support the idea of Python being capable of the same level of performance or actively supports the opposite.

> PEP 658 went live on PyPI in May 2023. uv launched in February 2024. uv could be fast because the ecosystem finally had the infrastructure to support it. A tool like uv couldn’t have shipped in 2020. The standards weren’t there yet.

> Other ecosystems figured this out earlier. Cargo has had static metadata from the start. npm’s package.json is declarative. Python’s packaging standards finally bring it to parity.

Are there any tools written in Python since then that are anywhere as close to as fast as uv when operating on packages that use this newer format? I've yet to hear of one.

> No .egg support. Eggs were the pre-wheel binary format. pip still handles them; uv doesn’t even try. The format has been obsolete for over a decade.

It seems dubious that adding support for egg would prevent uv from being as fast on packages that don't use that format.

> Virtual environments required. pip lets you install into system Python by default. uv inverts this, refusing to touch system Python without explicit flags. This removes a whole category of permission checks and safety code.

Passing `--user` to `pip install` doesn't seem to make things noticeably faster in most cases.

> Parallel downloads. pip downloads packages one at a time. uv downloads many at once. Any language can do this.

Any language with a global interpreter lock certainly can't do that as effectively as a language without one.

> Python-free resolution. pip needs Python running to do anything, and invokes build backends as subprocesses to get metadata from legacy packages. uv parses TOML and wheel metadata natively, only spawning Python when it hits a setup.py-only package that has no other option.

This one is pretty self-explanatory.

The section at the end somewhat overlaps with the parts I called out, and I recognize that the author of that post is almost certainly more familiar with the specifics of uv and Python package management than me, but with a lack of concrete example of a Python package manager that's anywhere close to the level of performance of a Rust one, I can't help but feel like pip would probably be quite noticeably slower than a Rust alternative written with an identical feature set (whether that feature set is "what pip currently supports" or "the minimal set of features described here"). I could imagine it being something like, pip could maybe be optimized from being 50x slower than uv to only 5x, but if that's the case, I think "Rust isn't the main reason it's fast" is a bit of an oversimplification when the discussion is about comparisons to alternatives that are all written in Python.