Web Browser Hogging CPU After WordPress Upgrade

I recently upgraded to 2.9.2 and suddenly my web browsers are using large amounts of CPU when I am writing a blog entry. The CPU utilization due to the browser spikes to nearly 50% in a periodic manner, peaking perhaps every three seconds ago.

I cannot say for certain that the problem is due to the WordPress upgrade since I also installed several plugins at the same time. But I have no idea how to debug this problem.

Can anyone offer suggestions?

Scott