The Culprit Is...

I've had some serious slowdowns occurring on my computer and had one hell of a time trying to figure it out. I would bring up the task manager (ctl/alt/del) and sort the processes by CPU time with highest on top (click the cpu column heading twice). It became obvious the FireFox was really eating up 100% of the cycles.

From blogspot

Here you can see what happened as soon as I closed FireFox. Some web searching provided nothing useful except to show several people have had this problem. I disabled some of my addons I really didn't need. Each time I started FF the problem came back. I tried starting FF in safe mode but it still happened.

Now I was allowing all my tabs to be restored each time. I had roughly twenty open. I left task manager up and started closing tabs slowly, watching the CPU usage. Turns out it was one site, SFGate. I had left a story open I was interested in. Doesn't matter what I do, anytime I have a SFGate page open it happens. Now I have some ad blockers and no script installed but it seems that might not be it. After all it still happens when I tried safe mode which disables all blockers.

I also tried Chrome, IE8 and Opera with the SFGate home page. Each showed an initial sharp spike in task manager but then settled down. Opera showed a somewhat higher usage with up and down spiking at around 20-25%.

Interesting and I'll still keep using FF as my default browser since I like it and am used to it. It should be interesting if I find any other pages with this happening. The underlying cause remains a mystery.