Suddenly very slow performance – SLOOOOOW database performace
Installation and Configuration
If optimizing your debug table took a long time, see whats in it. on my sites its almost always empty. If its filling up you might have left over debugging code in place.
Wipe out the activity log too if its big. Only really useful to help you understand whats going on at the moment. Pretty sure I've never gone back more than a month or so to see what was happening last month in the activity log.