Firefox has the reputation of being very demanding in terms of system resources and bringing this consumption to the level of a much lighter and more performing browser can be very difficult. However, during a normal web browsing session, if your computer's CPU usage is constantly at 100% it means that something is not working properly. Extensions and add-ons are the most common causes of this type of problem, but even a simple change in configuration settings can be a huge help.
Steps
Part 1 of 3: Troubleshooting Extensions Related
Step 1. Start Firefox in Safe Mode.
Type the following about: support into the address bar. The "Troubleshooting Information" page will be displayed. Press the Restart button disabling add-ons…. When the pop-up window appears, choose the Start in Safe Mode option. During this operating mode all add-ons are disabled. Browse the web as usual, monitoring CPU usage. If Firefox's CPU usage has dropped, continue reading the next step. If not, try using another method among those described in this guide.
You can also reach this page by accessing the main Firefox menu, choosing the "?" and selecting the "Troubleshoot" option
Step 2. Disable an extension
Restart Firefox in normal mode. To do this, close all open windows and reopen them. Type the following string about: addons into the address bar. The Manage Add-ons page will appear. Choose the "Extensions" tab, then press the Disable button for the extension you want to temporarily disable. If a browser restart is required, do so. At this point, try to navigate as usual while keeping CPU usage under control.
- At this link you can find the list of all known extensions that generate problems, together with the relative solutions. The list isn't complete or up-to-date, but it's still a great place to start.
- Most of the extensions that commonly cause this type of problem include antivirus, ad blocker filters, and Adobe Reader add-ons. Start by checking these programs first.
Step 3. Repeat the checks with the other extensions
If the CPU usage has not decreased, continue by disabling another add-on, then continue with normal navigation. Repeat this step until the CPU usage percentage decreases. When this occurs, the last disabled item could be the cause of the problem. Don't re-enable use until you really need to. [Image: Stop Firefox from Consuming CPU Cycles Step 3 Version 7-j.webp
Using a large number of add-ons at the same time can overload your CPU, even if there isn't one that is actually malfunctioning. In this regard, the recommended solution is to disable all less used extensions and add-ons
Step 4. Set the default theme usage
If the problem persists, it could be because of using a custom theme. From the "Manage add-ons" page, access the "Appearance" tab to set the use of the default theme again.
Part 2 of 3: Troubleshooting Plugin Issues
Step 1. Update the plugins
To check the status of the plugins installed on Firefox, access the following web page. If you notice any Update Now buttons, press them and wait for the update phase to complete. When finished, restart Firefox. Plugins can increase the percentage of CPU used by the browser, especially when watching videos or browsing PDFs or other multimedia content.
Step 2. Change the behavior of the plugins
After updating them, you can test their correct functioning by following this simple procedure:
- Go to the "Plugins" tab of the "Manage Add-ons" page.
- Access each of the drop-down menus labeled "Always Activate", then select "Ask Before Activating".
- Browse the web as you normally do. Whenever the use of a plugin is requested, you will see a small window appear requesting its activation. If by pressing the "Yes" button the CPU usage goes up, it means that the plugin in question is the cause of the problem.
- Once you've identified the source of the problem, search for an alternative plugin that performs the same function. If the search does not lead to any results, leave the plugin in question in the operating mode "Ask before activating".
Step 3. To troubleshoot content issues, install a content extension
One of the common solutions is to block unwanted content from being displayed. Try using these extensions:
- If Flash content is the cause of the problem, please install "Flashblock".
- If JavaScript is the cause of the problem, please install "NoScript". This extension requires some work as problematic scripts have to be manually disabled one by one.
- In general, to keep CPU usage low, install "Adblock Plus" or another similar extension.
Step 4. Reset Firefox.
If all the solutions proposed so far do not work, restore the initial configuration of Firefox. This procedure permanently deletes installed add-ons, but most custom preferences and favorites will remain unchanged. To reset, access the following about: support page again and press the Reset Firefox button.
Before proceeding to restore the browser, it is however advisable to try to adopt the solutions proposed in the next section of this guide. If starting Firefox in safe mode the problem goes away, it is almost certain that the cause is to be found in a malfunctioning add-on
Part 3 of 3: Workarounds
Step 1. Change the version of Firefox you are using
Download and install the latest update available for Firefox. If you already have the latest available version of the browser installed, install Firefox Beta. The beta version of any software includes updates, features and fixes that have not yet been included in the standard version.
Restoring a previous version of Firefox is not recommended as it leads to information security risks
Step 2. Delete viruses and malware from your computer
If you notice suspicious pop-ups and advertisements while browsing web pages normally, your computer is infected with malware. Even if there are no obvious signs of the infection, run a scan with an antivirus program. These types of programs could be the cause of excessive CPU usage.
Step 3. Disable Windows "Compatibility" mode
If you are using a Windows system, right-click the Firefox icon on the desktop. Choose the Properties option, then go to the "Compatibility" tab. If the check button in the "Compatibility mode" box is selected, deselect it and restart Firefox.
Step 4. Enable hardware acceleration
This functionality delegates much of the calculation process to the video card, theoretically freeing the CPU from this onerous task. This usually works, but it could make things worse by browsing certain websites or using computers with an outdated graphics card or operating system. Try using your computer for a full day with hardware acceleration turned on, then repeat the test with hardware acceleration turned off. At the end, analyze the results obtained:
- Type the following string about: preferences # advanced into the Firefox address bar. Alternatively, access the main menu (by selecting the icon characterized by three parallel horizontal lines), choose the "Preferences" option and finally access the "Advanced" tab.
- Select the "Use hardware acceleration when available" checkbox (uncheck it when you want to disable this feature).
- When finished, restart Firefox.
Step 5. Turn on hardware acceleration to view Flash videos
The player of content created in Flash may use hardware acceleration even if this Firefox setting is disabled. Select the element in Flash with the right mouse button, then choose the Settings item. Click the (View) tab on the far left of the window that appeared, then select (or deselect) the "Enable hardware acceleration" checkbox. Change this setting to match Firefox's.
Some websites related to video content use players created in HTML5 instead of the classic Flash. Also in this case they should be configured correctly according to the Firefox configuration
Step 6. Disable WebGL acceleration
This is a function very similar to hardware acceleration and is mainly used by applications that widely exploit the graphic aspect, such as 3D video games accessible via internet browsers. This feature combined with previous versions of Firefox is known to increase CPU usage, but with the release of the current versions this problem has been fixed. You can still try disabling WebGL acceleration to make sure it's not the cause of the problem:
- Type the following string about: config into the address bar. As the warning in the pop-up window states, if you don't know what you are doing, you shouldn't change any of the settings on this configuration page.
- Perform a search using the following webgl.disabled string (be careful not to change parameters with a similar name).
- Select the parameter in question with a double click of the mouse to change its value to "True".
- When finished, restart Firefox.
Advice
- Enabling the use of hardware acceleration normally reduces CPU consumption, but may not be effective in reducing overall power consumption.
- Hardware acceleration may be more effective after updating video card drivers.
