I'm still working on the logout problem, but thanks for continuing to post about this because I don't necessarily know whether little changes I'm making are having any effect (I only get logged out every now and then with IE, and never with Firefox).
As for site speed, there was three times the normal traffic yesterday and I suspect that slowed things down. I'm checking into server options as well as ways to optimize what we already have. Please start a new thread if you want to keep talking about slowness and severs. Keep posting if you're having logout problems.