What causes Firefox to run slowly? There could be several reasons. This article from MiniTool will explain why Firefox is sluggish and provide you with methods to resolve the "Firefox slow" problem. Continue reading to learn more.

Firefox requires significant system resources to download, process, and display web content. Occasionally, you may face the "Firefox is slow" issue on Windows 10/11. Why is Firefox sluggish? Here are some possible causes:

• An outdated version of Firefox
• Hardware acceleration
• Third-party antivirus software
• Cookies and Cache
• ...

Now, let's explore how to address this issue.

Related article: 8 Solutions – How to Fix Firefox High CPU Issue on Windows 10/11?

Solution 1: Clear Cookies and Cache

Outdated browser cookies, cache, and other website data can also lead to Firefox consuming more CPU than usual on Windows 11 systems. Therefore, you need to clear cookies and cache in Firefox.

To perform this task, you can try using the system booster tool – MiniTool System Booster. It can diagnose and repair common computer issues, clean junk files, and optimize startup for faster performance. It can also free up disk space and delete sensitive data beyond recovery.

This tool can clean only Internet-related junk and personal data, such as temporary files, cache, cookies, form autofill data, saved passwords, and more. Now, let's see how to clear cookies and cache with MiniTool System Booster.

Tip: Since this tool will remove your saved passwords, it's advisable to write down your passwords or save them elsewhere.

1. Close Firefox. Download and install MiniTool System Booster.

2. Launch it to access its main interface.

3. Click the drop-down menu to select the Deepclean option.

4. Click the START CLEAN button to proceed. You will see the NetBooster page and can click Skip. Then, you will reach the Internet Cleanup page.

5. To clear the cookies and cache of Firefox, check the Firefox cache files option and click CLEAN SELECTED.

Alternatively, you can clear cookies and cache directly on Firefox.

1. Open Firefox and click the menu icon at the top right.

2. Click Settings > Privacy & Security.

3. Locate the Cookies and Site data section, and click the Clear Data… button.

4. Select the items you wish to clear and click Clear.

Solution 2: Run a Virus Scan

One of the most frequent causes of the "Firefox is slow" error is the presence of a virus or malware on your device. It is recommended to run a virus scan to detect any potential threats.

1. Access Settings by pressing the Windows + I keys simultaneously.

2. Navigate to Update & Security > Windows Security > Open Windows Security > Virus & threat protection.

3. In the Current threats section, click Quick Scan.

Solution 3: Temporarily Disable Third-Party Antivirus Software

If you encounter the "Firefox is slow" issue on Windows 11/10, the problem might stem from third-party antivirus software. If you have installed one on your computer, it is suggested to disable it temporarily to resolve the error.

Solution 4: Switch to a Different Theme

Firefox loads extensions when it starts up, and many extensions add startup tasks. If there are too many extensions installed, this could result in Firefox using more system resources, thus slowing down its speed. You can switch to a different theme.

1. Open Firefox, click the menu button in the top right corner, and choose Add-ons and themes.

2. Select Themes and try to find a simple theme that won't consume too many resources and install it.

Solution 5: Update Firefox

We are continuously enhancing Firefox. The latest version is faster than ever before and includes fixes for many issues that could slow down your Firefox.

1. Open Firefox and then click the menu icon at the right upper corner.

2. In the drop-down menu, click Help button and choose About Firefox.

3. The About Mozilla Firefox window opens and then Firefox will check for updates and download them automatically.

4. After the download is complete, click Restart to update Firefox.

Solution 6: Disable Unnecessary Plugins from Firefox

Installed Firefox add-ons and extensions may be causing the "Firefox is slow" issue; you can disable or remove them and observe if the problem persists.

1. Open Firefox and click the menu icon at the top right.

2. Click the Add-ons and themes option.

3. Click the Extensions tab and find the extension that might cause the "Firefox is slow" issue. Click the three-dots and choose Remove.

4. Then, go to the Plugins tab and disable the plugins that you don't need.

Solution 7: Disable Hardware Acceleration

Another reason you might experience slowness in Firefox could be hardware acceleration. You can disable it.

1. Open Firefox and click the menu icon at the top right. Click Settings.

2. Under the General tab, scroll down to find the Performance section and uncheck the Use recommended performance settings box.

3. Then uncheck the Use hardware acceleration when available box.

Final Thoughts

This article has provided seven solutions to help you eliminate the "Firefox is slow" issue on Windows 10/11. You can try each solution one by one until the problem is resolved.

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