The results from other people who have looked into [the performance difference with the Windows patch] have been mixed, it's fair to say.
[...]
After days and days of very confusing results and multiple fresh Windows installs, I think we're getting somewhere -- or at least I think we are.
[...] I can confidently say that in its current state -- at least prior to the recent patch -- [Windows] 23H2 can be a bit broken with Ryzen, or really, it is pretty broken with Ryzen [causing reduced performance in some -- but not all -- titles]. The degree to how broken does vary, and there seems to be no rhyme or reason as to why this is.
It's really confusing as to how two Windows 11 installs, on the same system, configured in the exact same way, can deliver such different results, but only in some games. In fact, the variance between the games tested is just as confusing, and it makes diagnosing the issue extremely difficult.