I've got a test case. It runs a simple animation loop drawing many small textures to the screen.
I've not been able to run this on other machines, but I did find out more info.
You can get the test case here:http://kitfox.com/tmp/FBOTest.zip
While working with the test, I learned a few things:
-This bug only seems to appear when I have Firefox 5 open in the background.
-Whenever I'm using an FBO, rendering speed is always fast
-Whenever I'm not using the FBO and Firefox is open, sometimes the program runs fast and sometimes it runs slowly (by slow, I mean about 2 fps with a 640x480 window. By fast, the frames blur together)
-I think the longer Firefox has been open, the more likely my program is to run slowly - however, this is hard to test since I would need a couple of hours between tests. However, if I keep running the program with no FBO and Firefox open, I will sometimes get a slow run, even if I have just launched Firefox.
- I've not tried this with other web browsers. I have disabled hardware acceleration in Firefox.