[daemonologist]

uv has a lot of great features, but the dependency resolution is why I'm a fanboy. It can resolve trees that pip gives up on, and it does it 20x faster than poetry (100x faster than pip) - saves me half an hour on some big projects. All the python resolution and environment management and stuff is just gravy.

[jim33442]

Yeah, this is when it really matters that they wrote it in a CPU-performant language. There have been times I pointed uv at a random pip-managed GitHub project to rescue it because the author forgot to specify some versions and entire deps in requirements.txt. It even took uv a bit of chugging to find an overlap. Also wow, those packages had a lot of pointless breaking changes.

[saghm]

I don't do Python all that often, but I got sold on uv when a year or so ago I wanted to try to fix a small bug in a relatively niche Python open source I was trying to use, and it used a packaging tool I hadn't even heard of before (pdm). I was able to run `uv tool run pdm <whatever other arguments I needed>` without having to know anything about how pdm worked or worry about how to properly install yet another python tool and figure out whether I needed to be concerned about whether it might try to use system (or user local) versions of packages I had installed or get pointed at a magic hidden directory that I had to create first. When I realized I might never have to care about that ever again for any Python tool, I was hooked.

[jim33442]

Even Poetry wants you to install it via pipx, which is itself managed by pip. I'm not going to do that.

[foobarbecue]

Rust isn't the main reason it's fast. The main reason is willingness to break backwards compatibility. https://nesbitt.io/2025/12/26/how-uv-got-so-fast.html

[jim33442]

Even with that, uv took some time at 100% CPU during dep resolution, which I imagine would've been much slower if in pure Python instead. Unless pip's backtracking is already in C.

[zanie]

I don't think it's true at all that "dropping features" makes uv fast. As an author of uv, I think that particular section of the article is way off base.

[foobarbecue]

Copy that, thanks for the info. I was taking the article at face value.

[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.

[scorpioxy]

I've only seen pip give up twice and both times were due to bugs that were actively being worked on and the project dependencies were quite old. Perhaps that's why I am less impressed. Don't get me wrong, working faster without any downside is great. But I don't change dependencies all that often for it to matter if it does it in 5 seconds or 30.