Hi! I work on the Python distributions uv uses. Performance is really important to us and we're on the bleeding edge of performant Python builds. Our distributions use profile guided optimization (PGO) as well as post-link optimizations (BOLT). From my understanding, these are not enabled by pyenv by default because they significantly increase build times. It's possible there are some platform-specific build benefits, but I'd be surprised if it was significant.
I can set up some benchmarks comparing to pyenv on a couple common platforms – lately I've just been focused on benchmarking changes to CPython itself.
For what it's worth, I didn't notice a difference between my distro-provided Python 3.12 and the one I built from source - and enabling profile-guided optimization made only a slight difference. I haven't tested with the precompiled versions uv uses, so they could be slower for some reason, but I doubt it. On the other hand, my hardware is rather old, so maybe newer machines allow for significant optimizations that the system version wouldn't have. But I still kinda doubt it.
If performance is important to you, the ancient advice to profile bottlenecks and implement important parts in C where you can, still applies. Or you can try other implementation like PyPy.
I can set up some benchmarks comparing to pyenv on a couple common platforms – lately I've just been focused on benchmarking changes to CPython itself.