I haven't tried profiling or anything, but anecdotally I can say that if I have multiple radio logins going on an older desktop or a tablet/netbook that it rapidly becomes unusable, taking 30-40 seconds just to load up the page - frequently Firefox will warn "a script on this page has become unresponsive".
jQuery itself isn't that heavy, but you guys seem to have piled a huge volume of JS on this UI, and it really feels as though it needs some judicious pruning.
I don't think there has ever been a UI I disliked more than I dislike the ePMP UI. It's horribly slow. I also find it almost impossible to log into it from my phone because of the way the Username/Password dropdown works.