Firefox Running Slow?How to turn your Firefox Browser Blazingly Fast-Troubleshooting Tips and Addons

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Firefox is the second most popular web browser after Microsoft’s IE. Undoubtedly, firefox is the best. The browser includes tabbed browsing, a spell checker, incremental find, live bookmarking, a download manager, and an integrated search system.  You can use third party tools by adding them as a firefox extension. But adding so many add-ons can make your web browser run slow. Sometimes the browser utilizes high CPU which forces you to restart the firefox. There may be many other reasons for your firefox browser to run slow. The article talks about various troubleshooting tips and firefox extensions that can turn your browser blazingly fast like never before.

Speed Test for Firefox Browser.

Follow the steps below to test how much time your firefox browser takes before and after installing addons, extensions or tweaking the code or following the troubleshooting tips listed below in the next section of this article.


1)    Clear the cache of Firefox Browser. To do so navigate to Tools->Clear Private Data… and select ‘Cache’ from the ‘Clear Private Data’ dialog window. Press the button ‘Clear Private Data Now’

2)    Before you optimize Firefox, navigate to numion stopwatch and do a speed test on any URL like The time needed to load the site completely will be displayed to you in the browser window. Note down the time.

3)    Clear the cache of Firefox from the Firefox settings dialog again – this is very important! Now, close Firefox, and optimize your browser with any of the addon or troubleshooting tips listed below.

4)    Start Firefox again, and repeat the speed test on Note down the time again. Compare the displayed result with the result from the test before the optimization.


Preliminary Checks before installing addons or tweaking firefox settings.

Check Point-1 Check if profile folder has a series of sequentially numbered files.

Mozilla application writes certain files in the profile folder. When these files are read-only or locked, you may experience performance issues or other symptoms as multiple numbered copies of those files may be created. Check your profile folder to see if it has a series of sequentially numbered files.


Windows Vista Users

  • Click the Windows Start button, and type %APPDATA%\Mozilla\Firefox\Profiles\ in the Start Search box near the bottom of the Start menu, without pressing Enter. A list of profiles will appear in the top left of the Start menu.
  • Click on any of the profiles (e.g. xxxxxxxx.default) to open it with Windows Explorer.


Windows 2000 and XP Users

  • Navigate to Windows Start button, and select Run
  • Type in %APPDATA%\Mozilla\Firefox\Profiles\ then click OK
  • Double-click the profile folder to open (e.g. the xxxxxxxx.default folder).

The profile folder contains files like bookmarks.html, cookies.txt, prefs.js, mimeTypes.rdf, sessionstore.js (Firefox only), and other files and folders. You should not see multiple numbered copies of these files (“bookmarks-<n>.html”, “cookies-<n>.txt” “prefs-<n>.js”, “sessionstore-<n>.js”, “mimeTypes-<n>.rdf”, etc., where <n> is a number). Make sure you do not see any “<filename>.moztmp” files (“bookmarks.html.moztmp”, “cookies.txt.moztmp” ,”prefs.js.moztmp”, etc.) since these temporary files are normally cleared after file changes to the profile have been completed.

Multiple numbered copies and “<filename>.moztmp” files can be caused if files in the profile are read-only or locked. For example, if “cookies.txt” is read-only or locked, then the “cookies.txt.moztmp” temporary file will also be read-only or locked and a cookies-1.txt file will be created. Additional write attempts will result in cookies-2.txt and so on. If you find these types of files in your profile folder, remove the “read-only” attributes, if found, and delete any multiple numbered copies.

If you are using Panda or Norton Antivirus or Google desktop them make sure you remove the profile folder from their index. Read more about it here.

Check Point-2 Create a new Firefox Profile.

If you think the above check as a rocket science then you can create a new profile in firefox browser. The user data gets stored in a profile and with new profile you may experience faster browsing as compared to older profile.

If the new profile troubleshoots your problem then you can then transfer bookmarks, passwords, cookies etc to the new profile. It is important to note that you do not copy the extensions. It is advisable to re-install them.


1)    Close firefox browser completely by selecting File -> Exit from menu.

2)    Navigate to the Windows Start Menu (bottom left button) and then select ‘Run’. On Windows Vista, press “windows key+R” if you haven’t enabled the “Run command” option for the Start menu.

3)    Enter “firefox -P” (without quotation marks) then click OK.

4)    Click the ‘Create Profile…’ button on the ‘Firefox – Choose User Profile’ window that comes up

5)    Click ‘Next’ in the ‘Create Profile Wizard’ window that comes up.

6)    Type in a new name in the ‘Enter new profile name’ box (about 10 letters long) and click ‘Finish’.

7)    Make sure that the ‘Don’t ask at startup’ box is unchecked (you can change this later) and click the ‘Start Firefox’ box. Firefox will start with the new profile.

If the new profile solves your problem you can then transfer some data such as bookmarks, passwords, cookies etc to the new profile. It is important to note that you do not copy the extensions. It is advisable to re-install them. See recovering important data from an old profile

Check Point-3 Run Firefox in Safe Mode.

Some add-ons can also slow down Firefox browser. To make sure try running Firefox in safe mode. Safe Mode is a special Firefox execution mode that can be used to troubleshoot issues in Firefox. In Safe Mode, you can reset some settings or disable extensions and themes that might be the source of the issue. Issue can be diagnose easily by comparing Firefox behavior in normal mode to its behavior in Safe Mode.


How to start Firefox in Safe Mode?

1)    Close down Firefox completely: At the top of the Firefox window, click the File menu, and select the Exit menu item.

2)    In Windows, click Start, open the All Programs list, and navigate to the Mozilla Firefox folder. In the Mozilla Firefox folder, select Mozilla Firefox (Safe Mode).

3)    Firefox should start up with a Firefox Safe Mode dialog.


Note: You can also start Firefox in Safe Mode by clicking Start, selecting Run (or use the Start Search box in Windows Vista) and then entering the following in the text field:


firefox -safe-mode

Clicking the Continue In Safe Mode starts Firefox in its Safe Mode. For details about various options visit here.

Check Point-4 Troubleshoot Firefox add-ons and themes.

If your firefox browser is running fast in safe mode then firefox addons, extensions or themes are consuming memory and time. Visit Mozilla support to see how to troubleshooting extensions and themes. The article basically speaks about dropping the faulty extensions and updating the addons.


Check Point-5 Identifying other areas of high CPU Consumption.

Sometimes Firefox consume high CPU in order to download, process, and display web content. If high CPU usage occurs only while visiting specific websites, then following areas should be reviewed to identify the problem.

Flash – Websites like YouTube, Google Video and other online video websites require a plugin called ‘Flash’ to display the web content. This plugin is used to display animated or video content inside the web browser window. Flash plugin is updated regularly, and some websites require the latest version of the plugin to be used.

  1. Download and install the latest version of the Flash plugin.
  2. A Firefox add-on, called Flashblock, allows you to selectively enable and disable animated content on websites. If you do not want the animated content to be displayed then you must use this plugin to improve your browsing experience.

Adobe Reader – The Adobe Reader plugin enables the display of PDF documents inside the Firefox browser. If high CPU consumption occurs when you access PDF documents then-

  1. Update Adobe Reader. For more information, visit Adobe Reader.
  2. Configure Firefox to open PDF documents outside of Firefox. For details, see open PDF documents outside of Firefox.

JavaScript – Menus, sounds, and other features in web pages require JavaScript. Extensive use of JavaScript may require significant CPU usage. Use Firefox add-on, called NoScript, to selectively disable JavaScript on websites.

Adblock Plus – Flashing image banners and Flash ads consumes significant CPU and take additional time to load. It is advisable to block them, if you do not want them to be displayed. Well, the website may not look pretty as before. For details, visit Adblock Plus.

Check Point-6 Identify Windows Compatibility mode

Windows Compatibility mode enables the execution of Windows program in an environment that mirrors earlier versions of the operating system. For example, you can execute Firefox in a Windows XP environment that is running the program as if the operating system was Windows 95. Running Firefox on Windows in Compatibility mode has been known to cause high CPU usage. To stop Windows from running Firefox in Compatibility mode:

1.       Find the firefox.exe file. Navigate to C:\Program Files\Mozilla Firefox

2.       Right-click the Firefox icon and select Properties to open the Mozilla Firefox Properties window.

3.       Select the Compatibility tab, and make sure Run this program in compatibility mode for: is deselected.


Check Point-7 Delete Firefox ‘Prefetch’ Files.

In Windows XP and Vista, the operating system load many files during the boot-up process. When you reboot your PC again then rebooting uses prefetched files instead of loading individual pieces across multiple reads of the hard disk. This prefetch mechanism accelerates the overall performance of the computer.

The method may not be efficient for Firefox and can require significant CPU resources. You may experience faster performance by removing prefetch files on Windows XP or Windows Vista systems. The prefetch files are stored in C:\Windows\Prefetch\

Delete any filename beginning with: FIREFOX (For example,

If any of the above method does not work for you or being non-techie you find them difficult then you may try the following addons or extensions to make your firefox run faster. Following is a list of important addons available for free to optimize your firefox settings to make your browsing experience a better one.


1) FireTune description

Usually you will find many tips on web that suggest you to tweak the firefox settings manually, which is a time consuming activity and difficult for the novice user. With FireTune, you need to make the selection as it includes all the performance optimizations options. FireTune will ultimately boost the performance of Firefox browser.


Download FireTune.



2) FasterFox

FasterFox works on ‘Prefetch’ mechanism. ‘Prefetching’ is the silent loading of links in the background before you click them. This speeds up browsing because by the time you click a link it is already cached on your computer and there is zero load time required. FasterFox allows you to tweak many network and rendering settings such as simultaneous connections, pipelining, cache, DNS cache, and initial paint delay.

Download FasterFox Firefox addon or Fasterfox Lite. Visit mozdev for details about FasterFox


3) Firefox Ultimate Optimizer 1.1

Firefox Ultimate Optimizer and reduces the memory and CPU usage by firefox browser. It works with Windows OS only. Make sure you have admin rights on your system along with .NET Framework 2. Installed.


Download Firefox Ultimate Optimizer


4) Firefox Preloader 1.0.366

If your Firefox takes ages to load, try speeding it up with Firefox Preloader. The tool preloads certain elements of Firefox, so that the browser takes an amazingly shorter time to open when you launch it. You can also tweak the browser’s Internet options and other basic settings. Works with Windows OS only.


Download Firefox Preloader


5) Tweak Network 1.3

Tweak Network is a small utility that loads web pages much faster and allows you to increase the maximum number of simultaneous downloads from a site. With this tool, you can tweak the network settings to speed up the loading of web pages and increase the maximum number of simultaneous downloads from a site (the default is only four).


Download Tweak Network


6) Mozilla Optimizer 1.6.3

Mozilla Optimizer is a tool which optimizes Mozilla, Mozilla Firefox and Netscape settings in order to considerably boost page loading. Mozilla Optimizer enables HTTP Pipeling and Keep Alive to keep the TCP overhead low while retrieving the website content.


Download Mozilla Optimizer


8) ImgLikeOpera

With this extension you can disable all images, all but cached images or all images not loading from this site. ImgLikeOpera also allows you to choose which images you would like to load on a page.  This helps cut down on loading all the un-necessary, and often large, images on websites.Download ImgLikeOpera





The above tips have turned my firefox browser blazingly fast. What about you? Let me know if the tips listed above helped you in making browsing experience with firefox, a better one.

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