I also wrote a pure python validation library [0] that is much faster than pydantic. It also handles unions correctly (unlike pydantic).
Pydantic2 is indeed much faster than any pure python implementation I've seen, but it also introduces some bugs. And on pypy it is as slow as it ever was, because it falls back to python code.
I wrote mine because nothing else existed at the time, but whenever I've had to use pydantic I've found it to be quircky and to have strange opinions about types, that are not shared by type validators. Using it with mypy (despite the extension) is not so easy nor useful.