I always had issues with flash content lagging or freezing up. Even on websites like youtube, photobucket, etc
Googled and found that the culprit could be the Plugin-container of Firefox.
Here is the fix:
Open a tab in firefox, enter this in the address bar---> about:config
Click on I'll be careful...blah blah
Search for dom.ipc.plugins.enabled
Change the value to false. (Toggle)
Now create 4 new boolean entries with the given names and set them to false
(you can only do this one by one)
dom.ipc.plugins.enabled.npctrl.dll
dom.ipc.plugins.enabled.npqtplugin.dll
dom.ipc.plugins.enabled.npswf32.dll
dom.ipc.plugins.enabled.nptest.dll
I tested it on Firefox 7 and it works fine. Just wanted to share it with you guys
learn it from: