Why does Firefox consume too much CPU and memory resources?

October 8, 2019 |

greater than 13 minutes

Mozilla Firefox remains one of the most sophisticated browsers developed for the Windows operating system. It grew to be the default web browser on many Windows computers due to its powerful features and offerings. Despite Google Chrome’s takeover and dominance of the Windows OS browser marketplace, Firefox remains relevant as many users still rely on the it for their day-to-day internet-based activities—from shopping to social media engagements.

Mozilla has put a lot into maintaining Firefox’s competitive edge, releasing updates, especially Quantum, that challenge other browsers. One of its major sells was the resource-light capability that the company introduced in Firefox 57, which has since been improved on in later updates.

Every popular browser out there, including Chrome and Edge, will consume system resources at some point, especially when there are lots of open tabs and pages that require high-end graphics processing. The same goes for Firefox. The general browsing experience involves high graphics rendering to entice users with impressive aesthetics, clear images and animations, and optimized text, which might not bode well with the system’s overall performance. This is why it has always been a challenge for developers to balance appearance, performance, and speed.

So, if you’re using Firefox and expect to reap from some of its powerful features, you should expect your system to be stretched a bit, especially if you’re not using a high-end rig. That said, there are situations where the need for high CPU and memory usage are not called for, but the browser heavily consumes them anyway. If you’re a victim of this issue, we’ll show you things to do to keep the browser’s consumption of your system’s resources down.

Why Does Firefox Eat So Much Memory?

The Internet sees technological advancements every day, and browsers must be upgraded to adapt to these new innovative introductions. From security to speed, different improvements are rolled out regularly. Web-based applications and multimedia, as well as optimized graphical interfaces and interactions require more computing power and system memory. For example, most modern browsers, especially Firefox, come with advanced features, such as WebGL.

That’s not all; developers of web browsers must strive to improve the quality of the browsing experience by adding new and improved features. All these come together to constitute the reasons Firefox often takes up too much memory. For instance, again, if you’re using the pre-rendering feature in Firefox, which lets you preload web pages easily, the browser will have to load these pages on your system memory to fetch them easily.

Here are other factors responsible for Firefox’s high CPU and RAM usage

Too Many Tabs Open

Firefox will consume too much memory and spike your CPU usage if you leave too many tabs open at once. This issue is not exclusive to Firefox as it happens with other browsers. To make sure you don’t have to reload the web page on an open tab any time you switch to it, Firefox saves that web page to your system’s memory. This means that the more tabs you open, the more memory is required to store web pages.

Themes and Other Browser Add-Ons

Like other modern browsers, you have the option to change the look of Firefox. That said, certain themes tend to eat up your system resources when applied. Other add-ons, particularly extensions, can also spike the browser’s use of your computer’s memory and CPU.

Corrupt Browser Files

Have you ever wondered where browsing preferences and settings, such as Zoom are stored? Firefox saves these configurations in certain files in your Profile folder. Sometimes, these files become corrupt due to app crashes and other issues. These corrupt files usually go on to spike the browser’s CPU and memory usage.

The Multiprocess Firefox Feature

Firefox’s bid to improve performance saw it introduce a project called Multiprocess Firefox, Electrolysis, or e10s for short. Its main purpose is to make sure browser tabs run as a different process from the main Firefox UI. While this bid to improve performance is great it comes with the cost of memory consumption. The good thing is that you can always change the setting, and we’ll show you how.

How to Fix Firefox’s High Memory and CPU Usage on Windows 10

You should now understand that using the full features of Firefox requires a large amount of your system’s memory. That said, we’ll be showing you tips to reduce high Firefox memory and CPU usage when there’s no need for it.

Update the Browser

Your first step is to make sure the browser is up to date. Older versions tend to be plagued by certain glitches and bugs, especially when they are no longer compatible with some web-based mechanisms and features. Mozilla releases regular updates with performance in mind, and this might be the solution to the annoying issue.

You can update the browser by going to the Firefox website and downloading the latest version. You can also update Firefox easily by following these steps:

  1. Go to the Start menu and launch Firefox.
  2. Once it opens, navigate to the top-right corner of the browser and click on the menu icon (the three horizontal lines).
  3. Select Help at the bottom of the menu, then click on About Firefox.
  4. The About page of Firefox will now show up, and the browser will scan for updates. If you’re using the latest version, you’ll see the “Firefox is up to date” notification. Otherwise, it’ll automatically begin to download and install the latest version.

Restart Mozilla Firefox

The reason you’re experiencing increasing system memory usage by Firefox could be because the browser has been active for a long period. If you’re used to having long browsing sessions, a good practice would be to restart Firefox from time to time, as a fresh startup will clear the system memory.

You don’t have to worry about losing your browsing session as you can always pick up from your last visited web pages, using the Restore Previous Session feature. Once you restart the browser, click on the menu icon, then click on Restore Previous Session.

If you want, you can configure Firefox to restore your previous session automatically whenever you restart the browser. Follow these steps:

  1. Launch Firefox, click on the menu button in the top-right corner of the window, and select options from the menu.
  2. Go to the General pane of the Options tab and tick the checkbox for “Restore previous session” under Startup.
  3. Exit the tab and your settings will be saved automatically.

Use Less Tabs

As we mentioned, the more tabs you use, the more Firefox consumes your system’s resources. To prevent this, make sure you stick to a lesser number of open tabs.

Disable Add-Ons

The next step you need to take is to disable all the extensions and themes that you installed and enabled.

Extensions are applications designed to enhance your browsing capabilities and give you more personalized options. With these programs, you can revamp the look of your home page, change the behaviour of your browser, and do a host of other things.

Themes allow you to change the appearance of your browser, and to an extent, your web pages.

While these add-ons provide all that you need to make browsing more relatable and customized, they cause the browser to consume your system’s resources. Try disabling your themes and extensions and check if that solves the problem.

Once you open Firefox, click on the Open menu button and click on Add-ons. You can also use the Ctrl + Shift + A combo to open the “Add-ons Manager” tab. Once the tab opens, go to the left pane of the window and click on Extensions. Now, go to the right pane and disable all your extensions. Do the same for the Themes panel.

Restart the browser, use it as you normally would, and if the high memory usage issue doesn’t occur, then you have these add-ons to blame.

You can also start Firefox in Safe Mode to see if this resolves the problem. The Safe Mode process is basically the same as manually disabling your add-ons, but it’s a more straightforward and automated approach, and it will also disable other customizations that you put in place. The feature is used to troubleshoot issues with Firefox, including the high memory usage problem.

Click on the Menu button in the top-right corner, click on Help, then click on “Restart with add-ons Disabled…” and select Yes in the confirmation window. Once the browser gives you the options to either Start in Safe Mode or Refresh, choose the former. Firefox will now open without loading your add-ons and other custom settings. If the issue does not show up again, then you know that one or more of your add-ons and settings are responsible for the issue.

Refresh Firefox

Sometimes, the issue might have something to do with your current settings and personal preferences, and setting Firefox to default could help you resolve the problem.

When you refresh Firefox, your Profile folder, where Firefox stores your personal settings and information, will be removed and a new one will be created. However, you should note that important data will be saved.

Items such as your browsing and download history, bookmarks, cookies, web form auto-fill, passwords, and personal dictionary will not be removed. However, the Refresh process will remove items and settings such as toolbar customizations, themes and extensions, modified preferences, added search engines, device settings and security certificates, download actions, and user styles, among others.

Follow these steps to refresh Firefox if you’re comfortable with it:

  1. Launch the browser.
  2. Click on the Menu button (the three stripes in the top-right corner of the window), then click on Help.
  3. Under Help, click on Troubleshooting Information.
  4. Go to the top-right area of the tab and click on the Refresh Firefox button.
  5. Once you see the confirmation window, click on Refresh Firefox again.
  6. The browser will exit and reset itself, and then you’ll see an Import window, detailing your import info.
  7. Click on the Finish button to complete the process.

Make Sure Your Graphics Card Driver is Up to Date and Toggle Hardware Acceleration

Hardware Acceleration is a feature that most applications use on Windows to enhance performance. It involves tasks being passed on to other components, such as your GPU or Sound Card, from your CPU. This eases the stress on the CPU and makes things work smoothly in most situations.

Some Firefox plugins and the browser itself speed up web content display with the use of your graphics processing unit. This means they hand over intensive graphics-related tasks from your CPU to your graphics card to facilitate faster, higher quality web content, especially when it has to do with multimedia content such as streaming.

To get the most of hardware acceleration, however, your graphics card has to be compatible with the feature. If it’s not, you might need to update its driver and check. We’ll show you different methods involved in updating your graphics card driver.

Automatically Update the Driver

You can go through the automatic route by using a third-party application to scan your system for faulty or outdated drivers and install their latest versions. If your graphics card driver is out of date or has any issue, the app will pick it out and give you the option to update it.

We recommend that you use Auslogics Driver Updater, as it’s one of the best tools suited to this purpose. It is developed by a Microsoft Gold Certified Partner and is designed to work seamlessly with Windows 10. Using this program means your driver will be updated from a database that is regularly updated with recent driver versions that support your purposes.

The steps below will show you how to use the program:

  1. Download and install Auslogics Driver Updater.
  2. The program will automatically launch after the installation process and begin to scan your system for problem drivers. If it doesn’t launch, open the Start menu, search for it, then launch it and click the Start Scan button.
  3. Once the scan is complete, you’ll be shown a list of problematic device drivers. Your graphics card driver will be part of this list if it’s outdated, faulty, or missing.
  4. Click on the update button, and the tool will download and install the latest driver for your card.
  5. Reboot your system and check whether your card now supports Hardware Acceleration.

Use Device Manager

Normally, you should be able to update your graphics card driver via Windows Update. Go to the Settings home screen, click on Update & Security, then click on Check for Updates. If there are available updates for your system, especially driver updates, allow Windows to download and install them.

Apart from going through Windows Update, the other standard way of updating your driver is going through Device Manager. The steps below will walk you through the process:

  1. Right-click on the Start button and click on Device Manager.
  2. Once Device Manager opens, expand Display Adapters.
  3. Locate your graphics card under Display Adapters, right-click it, and then click on Update Driver.
  4. Once the Update Driver window shows up, click on “Search automatically for updated driver software.”
  5. Windows will now search for the most recent version of your graphics card driver on the internet. The driver will be downloaded and installed once Windows finds it.
  6. Restart your computer after the update completes and enable hardware acceleration.

Manually Update Your Driver

If Device Manager fails to install the latest version of your graphics card driver, you might be left with the choice of manually downloading and installing the driver yourself. This involves searching for the driver on the website of your PC’s manufacturer or your graphics card’s manufacturer and downloading and installing it.

It’ll be better if you download and install the driver from the website of your PC’s OEM because graphics card drivers are customized in most cases.

Now, Toggle hardware Acceleration

Once you’re done with the upgrade, activate Hardware Acceleration. If your graphics card still doesn’t support Hardware Acceleration, you’ll experience issues with the feature, including the high memory usage problem. Follow these steps to turn off Hardware Acceleration in the browser:

  1. Open Firefox, click on the Menu button, then click on Options.
  2. Once the General panel of the Options tab opens, scroll down to the Performance section.
  3. Uncheck the checkbox that says, “Use recommended performance settings,” then uncheck the box next to “Use hardware acceleration when available.”
  4. Exit the tab and your settings will be saved.

Prompt Firefox to Minimize Its Memory usage

Mozilla Firefox has a built-in tool that you can use to reduce the browser’s memory usage. You’ll find this tool in the “about:memory” page, where you can also measure the browser’s memory usage, save a memory report, and differentiate between two memory reports.

Type “about:memory” (no quotes), into the address bar of Firefox and hit the Enter key. Once the page opens, click on the “Minimize memory usage” button under Free Memory. You’ll see the completion message that reads “Memory minimization completed” followed by the date and time the process was performed. Exit the tab and check if the issue has been resolved.

Remove Corrupt Files

We mentioned earlier that Firefox saves your settings and personal data in the Profile Folder, and that you might be dealing with corrupt files. One of the files that are known to be prone to corruption is the Content-prefs.sqlite file, which is used to store individual website settings. Try deleting the file and check if the issue persists. Before you proceed, please note that certain settings, such as Zoom might be cleared. Follow these steps to proceed:

  1. Once you open Firefox, click on the three horizontal lines (Menu button) in the top-right corner of the window and select Help.
  2. Under Help, click on Troubleshooting Information.
  3. Once the Troubleshooting Information tab opens, go under Application Basics and click on the Open Folder button beside Profile Folder.
  4. Once the folder opens, scroll to the Content-prefs.sqlite file, right-click it, then press and hold the Shift key on your keyboard before clicking on Delete.
  5. Relaunch Firefox, and a new file will be created.
  6. Check if the problem occurs again.

Use the Firefox Task Manager

Firefox has its own Task Manager where you can find out how much system resources are used by your tabs, extensions and other browser processes. You can stop individual processes that you find to be consuming too much RAM and CPU through the Task Manager.

Click on the Menu button, click on More, then select Task Manager. You can also summon the Task Manager by opening a new tab, typing “about:performance” (no quotes) into the address bar, and hitting Enter. Once the Task Manager tab opens and lists all the running tabs and browser processes, check which item is consuming your system’s resources the most. To end the process, place your mouse pointer over the item, then click on the “X” mark at the far right of the item.

Modify the Content Process Limit

Normally, each browser tab runs as a standalone process under Firefox. This is done to enhance the browser’s performance, increase security, and prevent crashes. For example, if all the browser tabs are tied together with the Firefox UI, everything will crash when one encounters a problem. As great as this feature might sound, it’s often the reason for Firefox’s high CPU and memory usage.

To resolve the problem, try limiting the number of processes that can run at once to 1. This tweak had solved the outrageous memory consumption issue for many users. Follow these steps:

  1. Launch Firefox.
  2. Click on the Menu icon and select Options.
  3. Scroll down under the General panel to the Performance section.
  4. Uncheck the checkbox for “Use recommended performance settings.”
  5. Now go to the Content Process Limit drop-down and select 1.
  6. Exit the tab and check if the problem persists.

Additional Tips

Try shutting down other applications that you’re not using to improve Firefox’s performance. Some of these programs might be contributing to your system lag. Go to Task Manager, locate any running background process that you’re not currently using, click on it and click on the End Task button.

Use Auslogics BoostSpeed: System slow-downs and lag issues are often the handiwork of junk files and broken system registry keys. Having a tool like Auslogics BoostSpeed will see your computer free from these entities. The tool will also enhance your browser’s performance as well as your system’s general health.

Upgrade Your RAM: Firefox might be using as much memory as it ideally needs to. The problem could be that your system memory is too low. If this is the case, try upgrading it. Most systems come with a single RAM stick, and you can add an extra stick to increase your computer’s memory. To check if any slot is empty, follow these steps:

  1. Launch Task Manager, using the Ctrl + Shift + Esc combo.
  2. Once Task Manager opens, switch to the Performance tab.
  3. Click on Memory on the left side of the Performance tab.
  4. You’ll now see the details of your system memory.
  5. Look for the “Slots used” detail and check if you have an extra slot.

If you don’t have an extra slot, don’t despair, as you can always change both slots! That said, make sure you confirm from your manufacturer’s website how much RAM you can upgrade to.


We believe that Firefox won’t hog your system’s memory and CPU anymore. If you have any thoughts on the browser’s performance, let us know through the comments section below.

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