Firefox uses too many CPU resources - How to fix
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 CPU (Central Processing Unit) is the "brain" of the computer. When the CPU is being heavily used, the overall performance of the computer can be impacted.
- Depending on your operating system, you can review and monitor CPU usage through specific tools. On Windows, the Performance tab of the Windows Task Manager displays the rate of CPU consumption.
Table of Contents
Updating to the latest version
The latest Firefox version includes improvements about CPU usage. Update to the latest version.
Extensions and themes
Disabling CPU consuming extensions and themes
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.
- For more information on starting Firefox in Safe Mode and on how to find which extension or theme is causing your problem, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.
Hiding intrusive content
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). To prevent automatic loading of unwanted Flash content, use the "Ask to Activate" setting in the Add-ons Manager Plugins panel. See the Set Adobe Flash to "click to play" on Firefox article for details.
Some extensions allow you to hide unneeded content:
- Adblock Plus and uBlock Origin allow you to hide ads on websites.
- NoScript allows you to selectively enable and disable all scripts running on websites.
Disabling CPU consuming plugins
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 . The Add-ons Manager tab will open.
- In the Add-ons Manager tab, select the panel.
- Click on a plugin in the list to select it, then select to disable it.
- Repeat for some of the plugins in your list.
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.
Checking Flash hardware acceleration
For certain plugins that play videos such as Flash, the content rendering in full screen can be accelerated by hardware. It eases CPU usage.
- Navigate to a page that shows a Flash video.
- Right-clickHold down the Ctrl key while you click on the video player and click in the context menu. The Adobe Flash Player Settings screen will open.
- Click on the icon at the bottom-left of the Adobe Flash Player Settings window to open the Display panel.
- Check Enable hardware acceleration is selected.
- Click to close the Adobe Flash Player Settings Window.
Checking Firefox hardware acceleration
Firefox hardware acceleration eases CPU usage.
- Check that hardware acceleration is turned onturned on and that your graphics drivers are up-to-date.
Corrupt content-prefs.sqlite file
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 and select .From the The Troubleshooting Information tab will open. menu, choose .
Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.
- Under the Application Basics section, click on A window will open that contains your profile folder.Your profile folder will open. .
Click the menu button and then click ExitQuit .
Click the Firefox menu , then click .Click the Firefox menu at the top of the screen, then click .Click the Firefox menu , then click .
- In your profile folder, delete the file content-prefs.sqlite. It will be recreated next time you open Firefox.
Based on information from Firefox CPU usage (mozillaZine KB)