I have long been a proponent of the Firefox browser and a regular user of it since well before the official first release. This despite the few niggly little bugs that existed in the early days, mainly memory leaks and problems with Javascripts (actually I think some of those still exist). Even the need to regularly shutdown and restart Firefox to free up memory didn't deter me from using it as my preferred browser.

However the recent upgrade to version 2.0.0.1 seemed to introduce a new issue that proved to be a real show stopper as far a Firefox was concerned. I found that after Firefox had been open for a while it would start consuming every available CPU cycle on the machine (which, by the way, has 512Mb RAM and is running Windows Home Edition with SP2) and effectively ground the PC to a halt. So much of an issue was this that I had to switch back to IE7 while I tried to resolve the problem.

First step was to check the Mozilla Support Forum to see if this was an isolated event or was anyone else was experiencing this issue. There a found a lengthy thread under "2.0.0.1 performance problem" that indicated I was not the only user experiencing these problems. The thread also suggested an number of varied possible causes for the problem including:

The Flash plugin (this from Robert Lindsay's blog "Fix For a Nasty Firefox CPU Bug ")
A variety of Firefox extensions
Using WYSIWYG rich text editors
Conflicting Firefox profiles

So that gave me a number of possible root causes for my CPU usage problem. Well I typically don't visit sites with Flash so I thought it was unlikely to be the Flash plugin that was causing the issue. There is a Flashblock add-on that can be used to block Flash (you'd have never have guessed that would you); but as extensions are a possible source of the problem, and I didn't think Flash is an issue; I didn't want to install yet another possible culprit.