I am ardent fan of Firefox browser and been heavily promoting it ever since I started using it few years ago. Things went well and my browsing experience with Firefox is great.. until I upgraded to the latest Firefox 2 once it was make available for public.
Since then, I encountered a serious degradation of performance which includes:-
- Frequent hangs when switching to another tab
- Longer loading time compares to Firefox 1.5
- Occasionally send CPU usage to 99%
At first, I thought that it may due the extensions that I have installed but I do not encounter these problems when I am using Firefox 1.5 installed with the same extensions. In the meantime, until they solve the issue, I will re-install Firefox 1.5 on my PC. Hopefully, the upcoming Firefox 3 will offer a huge improvements over its predecessor. Still a Firefox fan though. 
Do you encounter similar problem? Post your comment here!
i also encounter these problems on my mac. damn
Wow, if it gives problem to a MAC, then it is a big issue bcoz I have this perception that MAC is a very stable computer which is true. You have a better option, Safari, at least.
I had that problem recently, until I realized that it was due to my Firewall (I was using Comodo Firewall Pro), after uninstalling that, I had no problems with my Firefox ever since I switched back to my Sygate Firewall.
Firefox does have some memory and cpu issues though, but a lot of that is attributed to the addons we use. I’m willing to live with it because some of the addons I use are known to eat a lot of memory but I’m fine with that.
I never have the two problems you mentioned.
@Edrei : I do not have firewall installed and both my PC in office and at home encountered the same problems. The one at home has less add ons. Do not know what is the reason.
@Jason : Great to hear that things are going fine for you.