We got positively hammered last night 
, which is why the site was slow. I've tweaked a few things and am looking at others, and I think it's doing a bit better now 
.
I've never had any problems with IE. Login stuff is cookie based, so it's most likely not a site issue. I mean, it's possible, but not particularly likely. It's hard to say either way without knowing your browser security settings, whatever blockers you might be using, and reports from others who are experiencing the same thing.