I.E.8 I only use for sites that seem to prefer it. It's OK. Firefox used to be fast but later versions seem slow. BUT - I find with FF that I add too many add-ons - start taking them off and it's back to speed. I've started using Chrome and it's fast so I'll give it a good try.
One thing - I've notice that Hotmail doesn't work as well with FF3.6.3 as half the time it doesn't like to forward or reply to messages without refusing to add the signature or keeping the original text in the message.