Why Is Mozilla Firefox So Slow?

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Firefox is Mozilla's popular Web browsing program. Slowness when first loading the program or during normal operations can be frustrating, especially if you frequently open links to Internet applications, which open in Firefox, from other programs. If your career or school work requires you to use the Internet, this slowness can also impede your productivity.



Firefox may load and operate slowly if you have installed many add-ons or if your add-ons are conflicting. You can disable all add-ons and enable them, one by one, to determine if a specific add-on is causing trouble. In addition to this, you may wish to check for updates to add-ons to ensure that your installed add-ons are compatible with your current version of Firefox. You may consider disabling add-ons when they are not in use and manually re-enabling them when you have a need for them. Another method that can help determine if extensions are an issue is running Firefox in safe mode. Instead of opening Firefox from a desktop shortcut, expand your programs list in the Start Menu and choose "Firefox (Safe Mode)" from the Mozilla Firefox list. If Firefox loads normally in Safe Mode, an extension may be the cause of slowness.


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Firefox may be slow if you have many bookmarks. To circumvent this issue, remove unneeded bookmarks. You can also export your bookmarks to a file, such as a Web page, and save them on your computer for future reference. Firefox will no longer have to load all your bookmarks when you start it. This change can help improve performance.



Mozilla's Firefox Web browser may run slowly, like any other program, if your computer is low on memory. You can right click the Windows Task Bar and select "Task Manager" to view how much memory Firefox is user. Periodically restarting the browser will help to reduce its memory usage, especially if you tend to have many tabs open at once, as will closing unused tabs. However, if Firefox continually runs slowly or even freezes, because a lack of memory, you can considering installing addition memory in your computer if the maximum amount of memory is not installed.


Internet Connection

Sometimes, Firefox may appear to be slow, but it may actually be due to your Internet connection or wireless signal. To troubleshoot this issue, you can use a separate browser -- such as either Internet Explorer or Google Chrome -- to determine if loading is slow across the board. You can also check your wireless connection, if you are using a laptop or cell phone with Firefox, to determine its strength. Although your Internet connection may have speed limits, you can improve a weak wireless connection by moving the access point -- a router or switch -- to a high, central location that is free from metal or moving your laptop closer to the access point to ensure no furniture or walls are in the way.


Duplicate Files

Occasionally, Firefox may save duplicates of some sessions in your profile folder. When this occurs, Firefox will have to process all the duplicate files when loading; this can significantly increase boot time. Saved sessions and preferences are two likely culprits. You can check to see if this is occurring by navigating to your Firefox profile. Type "%appdata%" (without quotes) into the Start Menu search bar or Windows run dialog, click to open "Mozilla," then "Firefox" and then "Profiles." Open the folder that has the same name as your profile. If you have only one profile, the folder will contain the word "default." Look for multiple, sequential "prefs" or "sessionstore" files. You can safely delete any duplicate files.