Every couple of days, I will see my Firefox using 99% of CPU and crash.
I am a web developer. My Firefox has all sorts of add-ons: Abduction, Firebug, Html Validator, ScapBook, Screen grab!, Web Developer, YSlow. So, I do not need YSlow to know why my Firefox is slow and tend to crash.
I have an idea: how about start two instances of Firefox, one with all the add-ons and the other one clean. I will use the clean one for normal web browsing, and the fully loaded one with development. And, guess what, there is already someone who has done this and posted a blog about it: Firefox: Run a Regular and Development Profile at the Same Time. I used the solution, and it works perfectly.