I'd ask for some help (as 1-4 a.m. I am not really up checking out the server).
From my logs, it seems like "normal usage" when I get on, and I see googlebots crawling, but that might only be a part of it.
The database (which went away, as you saw above) was loaded heavily with requests. Now, the question is "why". Normally this is because of a lot of page hits.
I disabled the "access denied kitty", so we are currently without fast-crawling-protection.
Hints that will help me:
* how many users are online
* did the site go slow rapidly?
* is it a specific time? or randomly? in the first case, get the atomic time (incl. time zone) for me to look up stuff, please
Most things would need to be done on my end.