I noticed if I watch a flash video in either firefox or chrome it cuts my hash rate down from about 240 Mhash/s to 110 Mhash/s. If I close the tab with flash in firefox my hash rate will go back up. I can reproduce this behavior at will. Is this normal? Are there any work arounds?
It's because Flash uses GPU acceleration. You'll encounter a slightly similar issue if your browser uses GPU acceleration as well. In both cases, turning the options off will solve the problem.