Choppy flash playback

I have Flash version 11.4.402.265 on a Windows XP SP3 (with latest updates).  I'm having trouble with Flash when watching Hulu with FireFox (bad) or Chrome (worse).  Initially the playback is good, but after the first or second commercial breaks, the Flash process jumps from 25-35% of CPU to 100% of CPU and the playback becomes very choppy and unwatchable.

I've tried cleaning the disk storage from the Global settings, and all of the other suggested tripe from Hullu.  Nothing works.  Restarting the browser fixes the problem for a while, but after 15-30 minutes the playback again becomes unwatchable.  It looks like Flash has a serious problem.  Watching movies that don't have commercial breaks doesn't have this problem until the next program starts and then the issue appears.

I've also noticed that the problem can sometimes be triggered by clicking on the Hulu feedback (yes/no) during the commercials.  This triggers the problem about 2/3rds of the time.  Either way it looks like recent Flash updates have serious bugs.