I'm guessing I'm doing something wrong, because it makes very little sense when reading the doc but in short, on my machine, the slowest parser is ua-parser-rs.

That's what I'm doing in ipython (but I have the same results just with the python interpreter, it's just easier to time it):

from ua_parser import parse
ua_string = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.104 Safari/537.36'

%timeit parse(ua_string).with_defaults()

• With ua-parser-rs:

734 ms ± 27.7 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

• With just google-re2

188 ms ± 10.9 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

• After I uninstall ua-parser-rs and google-re2

1.07 ms ± 33.3 μs per loop (mean ± std. dev. of 7 runs, 1,000 loops each)

I'm on ubuntu 24.10 with Python 3.12.7.

Do you have any idea what's going on there? Something related to the cache being reloaded on every call? I couldn't find a way to avoid that.