Firefox uses too much memory or CPU resources - How to fix

At times, Firefox may require significant system resources in order to download, process, and display web content. If you are experiencing periods of sustained high resource usage while using Firefox, this article presents some options for you to review.

  • The CPU (Central Processing Unit) is the "brain" of the computer.
  • The RAM (Random Access Memory) or Memory helps your computer perform multiple tasks at the same time.
  • When your system resources are being heavily used, the overall performance and stability of the computer can be impacted.
  • Depending on your operating system, you can review and monitor resource usage through specific tools. See the Use additional troubleshooting tools section below for more information.
Note: If you send performance data, Mozilla will gather data including memory and CPU usage, which will help make Firefox better for future versions.

Update to the latest version

The latest Firefox version may include performance improvements. Update Firefox to the latest release.

Restart Firefox

Firefox may use more system resources if it's left open for long periods of time. A workaround for this is to periodically restart Firefox. You can configure Firefox to save your tabs and windows so that when you start it again, you can start where you left off. See Restore previous session - Configure when Firefox shows your most recent tabs and windows for details.

Disable resource consuming extensions and themes

Extensions and themes can cause Firefox to use more system resources than it normally would.

To determine if an extension or theme is causing Firefox to use too many resources, start Firefox in its Safe Mode and observe its memory and CPU usage. In Safe Mode, extensions and themes are disabled, so if you notice a significant improvement, you can try disabling or uninstalling extensions.

Hide intrusive content

Many web pages have content you don't need, but which still use system resources to display its content. Firefox's built-in content blocking can help save resources by preventing third-party tracking content from loading. See the Content blockingEnhanced Tracking Protection article for details.

Some extensions allow you to block unnecessary content; for example:

Check Flash hardware acceleration

If Adobe's Flash Player plugin is installed, rendering Flash content in full screen can be accelerated by hardware. This can ease resource usage in case of a dedicated graphics card.

  1. Navigate to a page that shows a Flash video.
  2. Right-clickHold down the Ctrl key while you click on the video player and click Settings… in the context menu. The Adobe Flash Player Settings screen will open.
  3. Click on the icon at the bottom-left of the Adobe Flash Player Settings window to open the Display panel.
  4. Check Enable hardware acceleration is selected.
  5. Click Close to close the Adobe Flash Player Settings Window.

Use fewer tabs

Each tab requires Firefox to store a web page in memory. If you frequently have more than 100 tabs open, consider using a more lightweight mechanism to keep track of pages to read and things to do, such as:

Check Firefox hardware acceleration

Firefox hardware acceleration eases memory and CPU usage in many cases. Check in Firefox's performance settings that hardware acceleration is turned on. Also make sure that your graphics drivers are up-to-date.


Reduce the content process limit

With Multiprocess Firefox, also called electrolysis or e10s , Firefox runs web content for all tabs separately from the main Firefox process for increased security and performance. Using multiple content processes can further increase performance and minimize the impact of content process crashes. You can modify Firefox's performance settings to change the content process limit.

Fx55-56settings-Performance Fx64settings-Performance Fx66BetaSettings-Performance

The recommended maximum is four but you can set up to seveneight content processes; however, having too many content processes can slow down your computer, and consequently, Firefox.You can set between one and eight content processes. The default is eight. Having more content processes can improve performance when using multiple tabs but it will also use more memory. You can reduce the number of content processes if your computer is running out of memory.

Close other applications

Having many applications running simultaneously may cause your computer to run slowly and other applications to do so as well. By closing down some of the unnecessary applications, system usage will be reduced.

Delete 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 Fx57menu , click Help and select Troubleshooting Information.From the Help menu, select Troubleshooting Information. The Troubleshooting Information tab will open.
    • Under the Application Basics section next to Profile FolderDirectory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.
    Note: If you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.
  1. Click the menu button New Fx Menu and then click ExitQuit Close 29 .

    Click the Firefox menu Fx57Menu , then click Exit. Click the Firefox menu at the top of the screen, then click Quit Firefox.Click the Firefox menu Fx57Menu , then click Quit.

  2. In your profile folder, delete the file content-prefs.sqlite. It will be recreated next time you open Firefox.

Refresh Firefox

The Refresh Firefox feature can fix many issues by restoring your Firefox profile to its default state while saving your essential information. See Refresh Firefox - reset add-ons and settings for details.

Use additional troubleshooting tools

There are a variety of troubleshooting tools that can be used both in Firefox and on your operating system to troubleshoot elevated system resource usage.

Firefox tools

  • The Firefox Task Manager (not to be confused with Windows Task Manager) is a great tool to see what tabs and extensions are using the most system resources.
  • The about:memory page allows you to troubleshoot specific issues relating to memory (for instance, caused by a website, an extension, a theme, etc.) and sometimes its Minimize memory usage button may help you instantly reduce memory usage. For guidance on use of about:memory visit about:memory.
  • Even if you're not a programmer, you can try your hand at some other tools and tips Firefox developers use to debug leaks.

Operating system tools

  • Although it's not included on every distribution of Linux, most versions of Linux have a graphical resource monitor. It's often called System Monitor, but there are other alternatives also available.
  • Running the top command in the terminal will display a list of all the running processes and their system resource consumption.
WARNING: There are a variety of third-party programs that promise to increase your computer's performance. You should exercise caution when installing third-party software and only use reputable software provided by an official source.

Add RAM to your computer

If you exhausted all tips in the previous sections and your memory usage is still close to the maximum, maybe it's time for you to add more memory to your computer. Adding RAM will provide a huge performance boost.

Upgrade your computer

If you exhausted all tips in the previous sections and you are still experiencing high system resource usage, it may be time to upgrade your computer. As technology progresses, software is becoming more advanced and requires more powerful computers to run effectively.

// These fine people helped write this article:AliceWyman, Chris Ilias, Tonnes, Michele Rodaro, Tim, Michael Verdi, scoobidiver, Andrew, John99, TyDraniu, Swarnava Sengupta, soucet, Ashickur Rahman, Wesley Branton, Lan, Joni, Dinesh, Ömer Timur, Caitlin Neiman, yoasif, vmmunoz4. You can help too - find out how.

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