7 Best Fixes for Firefox High CPU Usage on Windows 11

Firefox is a popular web browser known for its speed, security, and customization options. However, it isn’t completely devoid of issues. Many Windows 11 users complain about Firefox consuming unusually more CPU resources whenever they launch the browser or use it for extended time.

Even if you don’t notice it while casually browsing, this increase in CPU usage can negatively impact your computer’s performance, preventing other applications from running smoothly. However, before making changes to remedy a sluggish experience, here are some solutions to fix high CPU usage for Firefox on Windows 11.

1. Close Unused Tabs

One of the first things you can do to reduce CPU usage for Firefox is close all the unused tabs in the browser. With multiple tabs open simultaneously, your computer tends to consume a significant amount of system resources, such as CPU and memory. That’s even higher if the tabs are related to video or audio streaming services.

2. Update Firefox

There’s a chance that you might have encountered a bug that is causing Firefox to utilize more CPU resources than usual. In such cases, you’ll need to check if there’s any new update available for Firefox that might fix the bug for you.

To manually check for updates in Firefox, follow the steps listed below:

Step 1: Press the Windows + S keys to open Windows Search and type Firefox. Then, from the result for Firefox, click on Open.

Step 2: Click the Hamburger menu located in the top-right corner.

Step 3: From the menu that appears, click on Help.

Step 4: Under the Firefox Help menu, click About Firefox.

Step 5: When the About Mozilla Firefox window opens, Firefox will automatically check for Updates.

3. Clear Browser Cookies and Cache

Outdated browser cookies, cache, and other website data can also cause Firefox to utilize more CPU than usual on your Windows 11 computer. We recommend clearing cookies and cache in Firefox before relaunching it to make it start fresh. Do note that doing that will make Firefox a bit slower initially, till it collects fresh cookies and data.

If you need help clearing browser cookies and cache in Firefox, follow the steps listed below:

Step 1: Press the Windows + S keys to open Windows Search and type Firefox. Then, from the result for Firefox, click on Open.

Step 2: Click the Hamburger menu located in the top-right corner.

Step 3: From the menu that appears, click on Settings.

Step 4: Under Settings, click on Privacy and Security.

Step 5: Scroll down and click on Clear Data.

Step 6: Select the check boxes for ‘Cookies and Site Data’ and ‘Cached Web Content.’ Then, click on Clear.

If clearing cookies and cache in Firefox didn’t help reduce the CPU utilization, move on to the next solution.

4. Disable Unnecessary Extensions in Firefox

Browser extensions or add-ons can improve your browsing experience with additional functionality. But, using too many extensions at once can lead to high CPU usage on your computer. Hence, if you have installed multiple extensions in Firefox, you will need to disable the unnecessary ones, as shown in the steps below:

Step 1: Press the Windows + S keys to open Windows Search and type Firefox. Then, from the result for Firefox, click on Open.

Step 2: Click the Hamburger menu located in the top-right corner.

Step 3: From the menu that opens, click on Add-ons and themes.

Step 4: Select the option for Extension from the left and disable the unused browser extensions by toggling them off.

5. Check if Hardware Acceleration is Enabled

Yet another reason you might be experiencing higher CPU utilization in Firefox might be due to Hardware Acceleration being disabled. If hardware acceleration is disabled, your CPU will have to push itself harder to perform graphics-intensive tasks that the GPU otherwise would have taken up.

To check if Hardware Acceleration is enabled in Firefox, you can follow the steps mentioned below:

Step 1: Press the Windows + S keys to open Windows Search and type Firefox. Then, from the result for Firefox, click on Open.

Step 2: When Firefox opens, click the Hamburger menu in the top-right corner.

Step 3: From the menu that appears, click on Settings.

Step 4: Scroll down to the Performance section. Then, check if the checkbox for ‘Use recommended performance settings’ is deselected and ‘Use hardware acceleration when available’ is selected.

If hardware acceleration is already enabled, you can disable it to see if that helps reduce the CPU usage. Although its function is to reduce the load on your CPU, it can sometimes cause more harm than good.

6. Try Using Firefox in Troubleshoot Mode

If you are experiencing high CPU usage when using Firefox, try running Firefox in Troubleshoot Mode. This will start the browser with default settings, without loading any add-ons or extensions you might have installed, helping reduce the CPU usage.

To run Firefox in Troubleshoot Mode, you can use the following steps:

Step 1: Press the Windows + S keys to open Windows Search and type Firefox. Then, from the result for Firefox, click on Open.

Step 2: Click the Hamburger menu in the top-right corner.

Step 3: From the menu that appears, click on Help.

Step 4: Under the menu for Firefox Help, click on Troubleshoot Mode.

Step 5: When a ‘Restart Firefox in Troubleshoot Mode’ prompt appears on the screen, click on Restart.

Step 6: Click on Open to launch Firefox in Troubleshoot Mode.

Suppose the problem is fixed in troubleshoot mode. In that case, you can exit out of Troubleshoot Mode and manually disable all the extensions before re-enabling them one by one to determine the one causing issues.

7. Reinstall Firefox

If none of the previous solutions work, there might be an issue with your Firefox installation, causing it to consume more CPU resources than usual. In such cases, you can remove Firefox and reinstall it from scratch. Here’s how you can do the same on your Windows computer:

Step 1: Press the Windows + I keys to open the Settings app.

Step 2: When the Settings app opens, click on the Apps option in the left sidebar.

Step 3: On the Apps page, click on the option that says Installed apps from the right pane.

Step 4: Type Firefox in the search box at the top.

Step 5: From the search results, click the horizontal three dots menu next to the Firefox result. Then, select Uninstall.

Step 6: Click the download button below to download the Firefox installer on your PC.

Download Mozilla Firefox for Windows

Step 7: When the download completes, click on the .exe file and follow the on-screen instructions to reinstall Firefox on your computer.

Prevent Firefox from Hogging Up the CPU

By implementing the solutions outlined above, you can effectively prevent Firefox from hogging up your computer’s CPU resources. This will allow your computer to allocate more resources to other important applications, even when Firefox runs in the background. Meanwhile, if you continue facing troubles with Firefox, we recommend replacing it with a Chromium-based web browser for Windows.