At times, Firefox may require significant CPU resources in order to download, process, and display web content. If you are experiencing periods of sustained high CPU usage while using Firefox, this article presents some options for you to review.
The latest Firefox version includes improvements about CPU usage. Update to the latest version.
Extensions and themes can cause Firefox to use more CPU than it normally would.
To determine if an extension or theme is causing Firefox to use too much CPU, start Firefox in its Safe Mode and observing its CPU usage. In Safe Mode, extensions and themes are disabled, so if you notice a significant improvement, you can try disabling or uninstalling extensions.
Many web pages have content you don't need, such as ads, but which still use CPU resources to display its contents (see the plugin section below). Some extensions allow you to hide bothering content:
To check to see if you have the latest versions of all your plugins, go to our Plugin Check page.
You can test to see whether one of your plugins is causing Firefox to use too much CPU by selectively disabling some of them:
Click the menu button and choose Add-ons. The Add-ons Manager tab will open.
After disabling some of your plugins, close and restart Firefox, and observe its CPU usage. If you don't see an improvement, you can enable those plugins again and try with a different set.
If you do see an improvement in Firefox's CPU usage after disabling a certain plugin, you may leave it disabled. If its use is widespread on Internet, try to find an alternative lighter plugin.
For certain plugins that play videos such as Flash, the content rendering in full screen can be accelerated by hardware. It eases CPU usage.
Firefox hardware acceleration eases CPU usage.
Firefox stores your data in various files in your profile folder. The file used for saving individual website settings might be corrupt. If you delete that file, your zoom level settings will be reset, but it should decrease CPU usage.
Click the menu button , click help and select Troubleshooting Information. The Troubleshooting Information tab will open.
Based on information from Firefox CPU usage (mozillaZine KB)