Firefox is SLOW?

Before you say that there are other questions of this subject, I am asking this because I found the other questions didn't help my situation.

Recently, my Firefox has been running really slow, for example, my yahoo mail takes a little to load, and other sites just take longer to load. My Internet Explorer is running normally, so I know it is NOT my internet connection. I have tried the browsers Opera and Safari for windows, and they all work fast. The thing is, I like how Firefox looks, and I like the way I have it customized. I just want my Firefox to run FASTER! (the way it should...) I have already tried to uninstall and reinstall, even older versions. This did not help.

What can I do to make it run how it should? Thanks!