Firefox Uses Too Much Memory - How to fix?

Mozilla Firefox Is Using Way To Much Memory. How To Fix It?

Mozilla Firefox is one of the most popular open-source web browsers which was known as Phoenix at first and it was a browser that contained features like download manager or tabbed browsing when these features were not present in other browsers. The newest version of Mozilla Firefox is called Firefox Quantum and it is a version number 60. Mozilla Firefox is a great web browser that offers a great number of various features and customization options and it is designed to be a fast and secure web browser. However, while the Mozilla Firefox browser's performance is excellent, it could slow down your computer and use too much of your computer's memory.

If you are reading this, then most probably you have noticed that Mozilla Firefox started to use way too much memory and your computer works slower. This can be very frustrating and make you want to switch to another web browser, however, there are some things that can be done about that. But first we would like to explain why it is happening at all, why your Mozilla Firefox is using too much memory and why it is not that abnormal as it may look at first.

Mozilla Firefox is a modern web browser, which means it is reliable, secure and fast. To keep up with today's standards web browsers must use various new technologies. One of the things that makes Mozilla Firefox reliable is that it is a multi-process web browser, which means it splits up different parts of the browser into processes. If, for example, some plug-in or tab crashes, then being a multi-process browsers allows it not to crash the whole web browser along with it. But, this requires to use more memory. Features like prerendering are also very useful and let you save time by loading pages faster, but this feature requires to use more memory as well. If you are using some extensions, then the browser will use even more memory.

Now you know that if you want Mozilla Firefox browser to provide you the best browsing experience, it needs to use quite a bit of your computer's memory. However, there are some things that can be done in order to reduce the high memory usage caused by Mozilla Firefox browser. Read the guide below and try out our described methods, and hopefully Mozilla Firefox will not be using that much memory after that. In this guide you are going to find descriptions with screenshots of Firefox Quantum version 60. If you are using older version, then some of the settings may look different.

firefox uses too much memory

Table of Contents:

Update Mozilla Firefox

The first thing we recommend you to try is to check for Mozilla Firefox updates and update it if there are any updates available. Is it possible that older versions have some bugs or performance issues. Newer versions usually offer improved performance and fixed bugs. In order to check for Firefox updates, open it and click the three stripes (Open menu) in the top-right corner, then click "Help" option.

 update Mozilla firefox step 1

A new contextual menu will show up, click the "About Firefox" option.

update Mozilla firefox step 2

Mozilla Firefox will start checking for updates. If there will be any updates found, Mozilla will install them for you. If you already have the latest version, then you will see "Firefox is up to date" status.

update Mozilla firefox step 3

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Disable Extensions

Now that you have the latest version, you can try to disable the installed and enabled extensions. Extensions are software programs that allow users to customize their browsing experience. By using extensions you can make Mozilla Firefox compatible with your personal needs or preferences. Extensions can (and some of them usually do) cause increased memory usage. To access installed extensions click the three stripes (Open menu) in the top-right corner again and select "Add-ons" from the contextual menu or simply press Ctrl + Shift + A keys on your keyboard.

disable extensions step 1

Click "Extensions" on the left pane and you will see all installed extensions, you can choose whether you want to disable or to remove them. We recommend you to disable all installed extensions, then restart Mozilla Firefox and see if it still uses too much of your computer's memory. If disabling extensions solves the problem, then you will know that one of the extensions (or more than one) is making Mozilla Firefox to use too much memory. If that is the case, enable installed extensions one by one to see which one is causing the problem and remove it permanently.

disable extensions step 2

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Minimize Memory Usage

There is a built-in tool in Mozilla Firefox that allows you to minimize memory usage. There is a page called "about:memory" that allows you to troubleshoot specific issues about memory, like issues caused by a website, a theme or an extension. This page allows you to view, save, diff and load detailed measurements of Mozilla Firefox's memory usage. It also allows you to do a global garbage collection or do a cycle collection or to save garbage collection or cycle collection logs. By minimizing memory usage using the "Minimize memory usage" tool you could possibly reduce memory usage in one click. To do so, type "about:memory" in Firefox's address bar and press Enter. Then click the "Minimize memory usage" button and see if Mozilla Firefox is still using too much of your computer's memory.

minimize memory usage

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Use Default Theme

A theme is an add-on which allows users to change the visual appearance of Mozilla Firefox. It simply changes how the browser looks and it may make Firefox look not like Firefox at all. However, some themes could be more complex and fore Mozilla Firefox to use more memory. If you are using some kind of theme that is not a default theme, then we recommend you to switch back to the original, default theme. Click the three stripes in the top-right corner and select "Add-ons" again. Now select "Themes" on the left pane and make sure that the "Default" theme is enabled.

use default theme

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Start Firefox In Safe Mode

Safe Mode is a mode in Mozilla Firefox (there is a similar one in Windows) that is usually used to troubleshoot and fix various problems with Mozilla Firefox. Safe Mode disables all installed add-ons like extensions, themes etc., resets some settings and turns off hardware acceleration. The main goal of Safe Mode is to find out if one of the disabled features is the culprit of the problem and then take certain actions if one of them was actually the cause. In order to start Mozilla Firefox in Safe mode click the three stripes in the top-right corner and select "Help" and then select "Restart with Add-ons Disabled...". You will be asked if you really want to disable all add-ons and restart, click "Yes".

start firefox in safe mode step 1

You will be given two options: Start in "Safe Mode" and "Refresh Firefox", select the first one and see if Mozilla Firefox is now using less of your computer's memory. If this solved the problem, then it means that some of the settings, add-on or extensions are causing the problem. If you select the second option, the "Refresh Firefox", then it will restore Firefox to its factory default state byt save your essential information.

start firefox in safe mode step 2

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Adjust Content Process Limit

As we mentioned in our introduction, Mozilla Firefox runs web content for all tabs separately from the main Firefox process, which allows to increase security and performance. Using multiple content processes (usually it is 4 processes) increases performance and minimizes the impact of content process crashes. However, while additional content processes improve performance when using multiple tabs, they also use more memory. We recommend you to try to change these default settings and adjust content process limit. In order to do so, click the three stripes in the top-right corner and select "Options". then scroll down through the General section until you find the "Performance". Uncheck the "Use recommended performance settings" option and set "Content process limit" from 4 (default) to 1. Restart Mozilla Firefox and see if the memory usage is now decreased.

adjust content process limit

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Adjust Preferences

About:config is a feature in Mozilla Firefox that consists of a list with application settings, also known as preferences. The thing is that many of these preferences are not available in Options or Preferences menu. About:config is a feature that allows users to access "hidden" preferences and adjust them. However, you should keep in mind that you are accessing these preferences on your own risk and know that these advanced settings can be harmful to the stability, security and performance of Mozilla Firefox browser. In order to adjust these settings type "about:config" in address bar and press Enter. Now scroll through the long list of preferences and find the "browser.tabs.remote.autostart". Double-click it to change its value from "true" to "false". Disabling this preference will disable e10s/multiprocess which could be the reason why Mozilla Firefox is using so much of your computer's memory. Restart Mozilla Firefox and see if it began to require less memory.

adjust preferences

Some other simple things you could try is to run less open tabs, in other words, close the unnecessary tabs and the memory usage should be reduced then. Check Windows Task Manager and see how many Mozilla Firefox processes are running, see if leaving only one Firefox process running reduces the memory usage. Hopefully one of the mentioned solutions solved the problem for you. If there is another method which helped you and reduced the memory usage caused by Mozilla Firefox, and it is not mentioned in our guide - do not hesitate to share it with us and with the others by leaving a comment in our comment section below.

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Video Showing How To Fix Mozilla Firefox High Memory Usage:

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About the author:

Tomas Meskauskas

I am passionate about computer security and technology. I have an experience of 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an editor for since 2010. Follow me on Twitter to stay informed about the latest tech news or online security threats. Contact Tomas Meskauskas.

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