I am an open source advocator whenever, wherever possible. Nodoubt Firefox is one of my favorites and have been using since v1.0. Full CPU consuming happened at times in the past. It's been several months that FF is running without a hitch. My simple solution, then, was to close and open it [I can't afford to look in the code. I downloaded it once when I tried to write FF extensions, but unfortunately wasn't able to give time.]. Two days back i downloaded Firefox 2 Beta, installed and using side-by-side with Firefox 1.5. Since then, i am again experiencing full CPU usage, with both the versions. I wonder why, these two versions reside at different locations. Process Explorer shows jpeg_fdct_islow thread is actually consuming CPU. Googling shows other FF users having some problem but not any address from the FF Community yet, as of 18 Sep, 06.