I noticed recently that my Firefox 3.0 was running quite slow on my home PC. I know that there's a ton of news about browsers fighting to be the fastest but I felt that my home Firefox was running slower than my work copy. After doing a quick scan over addons that I have setup at home I noticed that my list is a bit longer compared to the setup I have at work. I went and disabled a number of addons that I am not using on a regular basis and restarted Firefox. Wow, what a difference. It seems like Firefox is like 10x snappier than it used to be. I don't know exactly which addon caused the slow down and don't want to create speculation. If your Firefox feels a bit sluggish then it's definitely worthwhile to go through your addons and disable or uninstall the ones you are not using.
Note: Firefox also has a
Safe Mode option that can also help if your Firefox is misbehaving or freaking out. It might also be something to look into to see just how fast things load and run without any extensions running.
Gena01