Anyone else have this problem..

I'm having this problem and it doesn't make much sense to me. Whenever I am on Facebook/using Facebook chat on my UMB (Firefox) it goes insanely slow, and beachballs constantly. I have upgraded my memory to 4GB, and am running SL. It never beachballs at any other time AT ALL unless I am on Facebook/using Facebook chat. It pretty much freezes the whole computer, I type something in the chat window and it will freeze, start typing one letter at a time extremely slowly, freeze again, then finish it off. It is then fine for about 5 seconds and starts it all over again. It's very frustrating because I basically can't go on FB on my computer. Anyone have any idea what could be wrong?