Go to a page on your browser that shows a Flash video, right-click on the player and select Settings. If you have the Adobe Flash Player plugin installed, it could be the cause of the high memory usage. Check Adobe Flash Player and Firefox Hardware Acceleration If it doesn’t happen in Safe Mode though, then it’s likely that the add-ons are the culprits. If the issue persists, it’s probably not caused by a theme or extension, but it could be because of preference settings or plugins among other causes, as these aren’t disabled in Safe Mode.
