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firefox runs slow but other browsers run fastFirefox is a great browser, and has been one of the most popular for years. When it was first released a great deal of the praise it received came courtesy of the browser’s speed and great standards compliance. At the time Internet Explorer was virtually unopposed, and it caused Microsoft’s development to stagnate.

Time doesn’t stand still however, and Firefox has matured over the years. This means great new features, but every change has the chance of causing a bug that degrades performance. Firefox shouldn’t feel slow, particularly when compared to Opera and Internet Explorer. If it does, try these tips and see if you can restore it to its full glory.

Step 1: Try Speedyfox

firefox runs slow but other browsers run fast

As you use and customize Firefox your data is stored in a profile, which is a SQLite database. Over time, customizations can pile on and the database can become slow, which in turn makes it so that Firefox runs slow but other browsers run fast. Plus there is always the slim possibility of an error or file corruption causing the issues with the database.

Speedyfox is a tool designed to solve this problem by compacting the database files. If you haven’t been using the browser for some time, it’s not likely that this will solve your Firefox woes. However, Speedyfox is a tiny download that takes seconds to run, so it’s worth a shot.

Step 2: Look For Troublesome Extensions

firefox runs slow

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One of Firefox’s greatest strengths is its extension support 7 Awesome Add-Ons That Only Work With Firefox 4 7 Awesome Add-Ons That Only Work With Firefox 4 Firefox has long been the darling of geeks everywhere, but its popularity has waned lately, mostly due to competition from Google's Chrome browser. Firefox, while stable and practical, simply wasn't as quick as Chrome. Some,... Read More . But that strength can sometimes be a weakness. There’s no Firefox police patrolling the extensions to make sure they all work together, that they all work with every version of Firefox, or that they work at all. It’s no surprise therefore that they can sometimes cause crashes, improper webpage rendering and performance issues.

Your first step is to check that extensions may be the source of the problem, which you can do by opening Firefox’s safe mode How to Use Mozilla Firefox in Safe Mode How to Use Mozilla Firefox in Safe Mode Read More . Click the Firefox button, then go to Help and select Restart with Add-ons Disabled.

If Firefox’s performance is suddenly improved, the problem is likely an extension. To find the culprit you’ll have to disable the extensions one-by-one in Firefox until the performance issues are resolved. It’s tedious, but necessary.

Step 3: Check Other Software

firefox runs slow

Another possible source of Firefox performance issues is interference from another program. Firefox is pretty well known, so anti-malware software shouldn’t interfere with it in most cases. But most cases are not all cases.

Simply disable your anti-malware software and see if this resolves the problem. You should also be sure to update all critical plug-ins, such as Adobe Flash. An outdated version can, in rare cases, cause performance problems.

If your anti-malware is the issue, open up the software(s) permissions and make sure Firefox is a trusted program and has permission to communicate through your firewall. This should solve the problem. If it doesn’t, try uninstalling the anti-malware temporarily and then install an alternative free antivirus The 10 Best Free Anti-Virus Programs The 10 Best Free Anti-Virus Programs Read More and free firewall The Three Best Free Firewalls for Windows The Three Best Free Firewalls for Windows Read More .

Step 4: Consider Hardware Problems

firefox runs slow

Web browsers are rarely limited by modern computer hardware, but it is possible that hard drive issues could cause Firefox to run slow while other browsers run fast.

First, check to see if Firefox is installed on the same hard drive as your other browsers. If it isn’t, your performance problems might be caused by a problem with the hard drive’s performance. This is a likely cause if your performance issues are limited to the browser’s load times. If Firefox is not installed on the same drive as your other browsers, reinstall it on the same drive.

Another possible problem is drive fragmentation 8 Best Defragmenters To Keep Your PC Running Like New 8 Best Defragmenters To Keep Your PC Running Like New Read More . This issue is not as common now that Windows performs scheduled defragmentation by default, but it’s still a possible sore spot on systems with Windows XP, or if you have disabled automatic defragmentation. The disk defragmenter can be brought up in Windows Vista or Windows 7 by searching for Disk Defragmenter in the Start Menu. XP users can find it by right-clicking on a drive volume, selecting Properties, and then opening the Tools tab.

Step 5: Nuke It From Orbit – Er, Reinstall

firefox runs slow but other browsers run fast

Reinstalling a program is the obvious final solution to any issue. It’s much like rebooting your computer to make a bug go away. It often works, but it’s far from elegant.

Using this as a solution is a tiny bit more difficult with Firefox because it conveniently saves all of your settings when you uninstall the browser. The browser you have when you reinstall will be basically the same as it was before.

It’s easy to solve this problem. There’s a critical checkbox labeled “Remove my Firefox personal data and customizations” that appears during the uninstall process. But fair warning – selecting it nukes everything related to Firefox, and you’ll be starting from scratch when you reinstall. Do this only as a last resort.


Hopefully these solutions will resolve your Firefox issues. They are in order from the least to the most extreme, so I recommend you follow them step-by-step. Don’t try two at once, or follow a solution half-way through. Fixing a bug causing performance issues means changing one variable at a time. Getting ahead of yourself could cause further headaches and false positives.

  1. anthony
    July 10, 2016 at 11:34 pm

    if firefox is slowing down and freezing and you have ad block or ad block pro uninstall it and install ublock. I have been uninstalling & going back to older versions withy no luck turns out it's that F'n Ad block. I would watch youtube and after a feww minutes my screen would freeze and have to do ctrl-alt-del. After dumping ad block and installing ublock no hangs anymore

  2. Paul McFate
    September 24, 2015 at 5:41 pm

    Okay, I will try the new Firefox for a while. So far, no problems on PC.

  3. Paul McFate
    September 24, 2015 at 5:39 pm

    I like what Firefox stands for. I love the ads. But when I try to load it, and it takes 15 seconds, I reach for Chrome. Firefox is always updating something just when I need it most.

  4. Thorsk
    May 4, 2015 at 7:39 am

    The second one worked for me, thanks!

  5. Mozilla Morons
    February 27, 2015 at 5:39 pm

    Step 6: Uninstall piece-of-crap Firefox and install another browser.

  6. Rglynn1
    August 5, 2011 at 4:41 pm

    Firefox is as big a joke as Chrome with it's message that it cannot connect.  That makes both of these browsers "not fast".

    • asdf
      June 6, 2016 at 3:08 pm

      If you're getting messages that your browser can't connect, you're doing something wrong.

  7. Rglynn1
    August 5, 2011 at 4:31 pm

    I have never knowingly added an extension.  Using FF 5.0.1. - 2yr old Macbook w/ 4 G mem. right now -  continually slows and stalls as multiple tabs stay open - stalls all applications - and the whole computer.  This has been a problem on Mac and PCs for prob'ly (at least) 3 yrs.  My "Fix" is to 'force quit' Firefox and then all is well.  Nothing has changed - this problem used to be called 'memory hog' problem (or something similar). 

  8. LSD
    June 16, 2011 at 2:50 pm

    Firefox 4 is horrible on old computers 3-4yr old machines or newer it should run fine but anything older your better off sticking with 3.6

  9. Alexandra Lawrenz
    May 19, 2011 at 3:33 pm

    Recently, browsers like Firefox have  become less cluttered, are faster when
    launching websites and include a ton of new features with every new release.
    However, I’ve noticed that certain add-ons still have a negative effect on all
    these great improvements. If you’re finding that Firefox is running slower, you
    should check for poorly written add-ons that might be causing this to happen.
    Mozilla actually created an entire site to list the top 9 low-performance add-ons, and you can check it out right here. I also put together a blog post
    that outlines how you can get rid of these slow add-ons if you’re interested:

    • Tina
      May 19, 2011 at 8:19 pm

      Thank you for the insight, Alexandra!

  10. Jagadish
    May 12, 2011 at 7:06 am

    @KiLotr:disqus. yeah creating a new profile will do the job. it helps you to run Firefox faster. here is how your can create a new profile without add-ons for Firefox in Windows

  11. Jagadish
    May 12, 2011 at 5:06 am

    @KiLotr:disqus. yeah creating a new profile will do the job. it helps you to run Firefox faster. here is how your can create a new profile without add-ons for Firefox in Windows

  12. Jack Cola
    May 11, 2011 at 6:11 am

    I am not sure about others, but after upgrading to FireFox 4, from FireFox 3.6, my browser, on multiple PC's because unresponsive more often.

    I am really thinking about downgrading FireFox. Does anyone else agree with me?

    • Tina
      May 12, 2011 at 9:45 am

      I cannot confirm your observation, Jack.

      For me Firefox became faster when I upgraded to version 4. I did have two or three occasions when Firefox froze, but I was playing with addons, so that may have been unrelated. No issues since, works great! Needs more system resources, but it's a lot faster and more responsive than the 3.x version.

    • joe popo
      June 1, 2011 at 6:53 am

      Yes you are right. Mozilla has issued an info about this glitch. This was caused by plugin-container.exe.

      • Jack Cola
        June 1, 2011 at 7:19 am

        Thanks for this. I noticed, especially on my mums laptop that when that hangs, I end task that program and it fixes itself up. I also have to end that .exe when Adobe reader doesn't load properly within FF.

  13. Philharmania
    May 11, 2011 at 1:51 am

    I simply don't believe you can speed up Firefox by reinstalling it. Instead, starting a new profile would be a better bet. Then again, I never care about the speed of my Firefox because internet connection speed is still my major bottleneck. I keep it open almost 24/7 on my Ubuntu machine and its performance is consistently satisfactory.

  14. Faizuddin Yusof
    May 11, 2011 at 12:31 am

    can it be used by cometbird?

    • M.S. Smith
      May 11, 2011 at 3:08 am

      I don't know, sorry. I haven't used Cometbird.

  15. Gonzalo Novoa (KiLotr)
    May 10, 2011 at 4:12 pm

    Creating a new firefox profile without addons is my favorite way to do it. run: firefox.exe -p and create a new fresh clean profile. I can't remember how to do it in OSX but last time it was a google search away.

    • Karen
      May 10, 2011 at 4:14 pm

      Great advice. Thank you :)

    • M.S. Smith
      May 11, 2011 at 3:07 am

      Yep, this work too. Worth a shot if Speedyfox doesn't do it.

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