I'm still experiencing the same slowdowns that
I reported more than 2 years ago, even when the US are still asleep.
More precisely, I'm still noticing the same delay the first time I access the forums (new session); it may be when the server has to create the 'ubbt_mysess' cookie. For example, accessing the site in anonymous doesn't have this particular problem.
It takes something like 10-20 seconds before the page loads, but sometimes there's no delay. This particular delay seems to point at the authentication code, which is usually heavier because of asymmetrical key algorithms, but it shouldn't be that much of an overhead (and the verification part is usually optimized). Perhaps it needs to create a key for the TLS session, too - Is this part performed by a different server? I doubt it but I'm not a specialist. Are bots registered (impacting the authentication system)?
Other than that, I occasionally have very long access delays for every page and time-outs when the US timezone is active and more people are there. I'm not visiting the forums regularly enough to tell whether this is always the case, or only around particular events like a PfH or a release. So that's probably a balancing issue or simply a capacity issue. I've seen a clear difference between 6:00 UTC and 18:00 UTC, several days. Are bots following a specific hourly pattern (impacting the servers in general)?
EDIT: interestingly enough, it just timed out a few times when I tried to post this.