Crap...I've been very big issue with Firefox 2.0 in the past few days due to the mediocre javascript performance of it. The RAM usage was out of this world (usually running over 400MB in task manager). Found out this was because of JavaScript. Maybe it is not solely Firefox's fault, but other browsers like Opera didn't express this kind of ghastly behaviour. Apart from the stupid RAM usage, the browser would start to wprl very very laggy when this happens. (not due to a endless loop, 'cos the CPU utilization is low; around ~5%)
The new Firefox 3.0 beta 1 build didn't show this kind of pathetic behaviour. However, I was really cornered because 80% of the damn addons I had installed in 2.0 didn't work. Though there is an addon that lets you bypass this protection, that addon itself wasn't compatible...how ironic
So, I installed Flock 1.01. This is also based on Firefox, and although the RAM usage hasn't improved very much (I can still get it to use 250MB RAAM

), it doesn't get laggy at all. And it's pretty cool; I mean the GUI.
So I'm now using Flock 1.01 (at least until Firefox 3 comes out)
Note: You will see this kind of behaviour if you are not browsing sites with heavy JavaScript integration.