5 Things to Do When Firefox Runs Slow (But Other Browsers Run Fast)

Mihir Patkar Updated 15-05-2019

Mozilla Firefox is still among the most popular web browsers today. But the more you use it, the slower it seems to get. So what can you do when Firefox is running slow while other browsers are still fast?


We’ve talked about some of the simple ways to speed up Firefox 9 Simple Tweaks to Speed Up Firefox Immediately Whether you're a long-time Firefox user or switching from Chrome, this quick guide shows how to speed up Firefox performance. Read More , and that’s where you should start. There are easy extensions for apps like disabling Pocket and other integrations, and finding the most memory-draining apps.

While these changes will make your Firefox faster than ever before, you still need to make sure it’s as fast as other browsers. So what can you do about that?

Note: Before you do any of these tweaks, you should download or update to the latest version of Firefox by going to About Firefox.

1. Firefox Takes Longer to Start Than Other Browsers

Set Firefox to show a blank page to make it start faster

Once you have had Firefox installed for some time, it can take a long time to start up. Meanwhile, browsers like Chrome, Edge, and Safari seem to launch immediately. Here’s what you can do to make Firefox boot faster.

  1. Go to about:preferences and in General, uncheck the box for Always check if Firefox is your default browser.
  2. Go to about:preferences and in General, go to When Firefox Starts and select Show a blank page.

2. Firefox Uses Too Much CPU or RAM

Firefox Safe Mode GIF - Find & Share on GIPHY

After using Firefox for some time, it starts using a lot of CPU process or RAM. To find out the cause of the slowdown, first try restarting Firefox in Safe Mode. This will make Firefox run without any add-ons or plugins. To do this, go to Options (the three-line icon at the extreme right of the URL bar) > Question Mark > Restart with Add-ons Disabled.

Firefox will restart and display two options: Start in Safe Mode or Refresh Firefox. Choose Start in Safe Mode.

If Firefox runs faster in Safe Mode, then you know the problem lies in one of the add-ons or plugins. Disable all add-ons, and restart Firefox. Then enable one add-on at a time, and see which one causes the problem.


In case Safe Mode doesn’t make any difference, then Firefox’s tabs are probably to blame. Install the Auto Tab Discard extension, which will automatically unload the resources used by an inactive tab. Rather than leaving tabs open to remember them, you can make better use of bookmarks.

Download: Auto Tab Discard for Firefox (Free)

3. Firefox Is Slow Even With Top-Notch Hardware

Change Content Process Limit in Firefox to make it faster

Firefox can sometimes run slow even on machines with excellent hardware. That’s usually because the browser is being conservative in how to improve your performance. But you can open up the hood and give that a boost.


Go to about:preferences > General > Performance. Uncheck the box for Use recommended performance settings.

  1. Check the box for Use hardware acceleration when available. With this tweak, Firefox will use the graphics card instead of the processor for major visuals. So whether you’re watching YouTube or playing a web browser game, you will get much smoother performance.
  2. Change Content Process Limit to four or more. Firefox recommends increasing it to more than four if you have at least 8GB RAM.

Content Process Limit is a function of Firefox’s new Electrolysis or multi-process architecture. With this, each tab runs as a separate instance of Firefox, thus getting access to more hardware resources. It also enables sandboxing for security.

5 Things to Do When Firefox Runs Slow (But Other Browsers Run Fast) firefox slow about config content multi process 670x129

In case the Content Process Limit is greyed out, you need to enable multi-process Firefox:

  1. Go to about:config
  2. Search for browser.tabs.remote.autostart
  3. Double-click it to change the Preference value to true
  4. Restart Firefox

4. Change Settings or Download Speed Tweaks

SpeedyFox applies common speed tweaks for Firefox

If you dive into about:config settings for Firefox, you will be able to change several aspects to speed up Firefox.

If you aren’t comfortable with messing around with settings, an extension will make sure you don’t break anything. Speed Tweaks changes a few settings, but not all. Once you install the addon, the best options to enable are pre-resolving DNS entries, discarding inactive tabs, and blocking ads.

Download: Speed Tweaks for Firefox (Free)

5. If All Else Fails, Refresh Firefox

How to Refresh Firefox to speed up

If all else fails, it’s time to go back to a clean installation of Firefox. But you don’t have to start from scratch all over again.

Much like operating systems, the browser now has a one-click option to return to the default Firefox state before you made any changes. Specifically, it will remove all add-ons and customizations, and restore browser settings to defaults.

  1. Go to about:support
  2. In Give Firefox a tune up, click Refresh Firefox…
  3. In the dialog box that shows up, click Refresh Firefox once again

Firefox will shut and restart in a few seconds. Smartly, while all the performance and settings revert to default, Firefox saves your personal information, including bookmarks, history, passwords, cookies, auto-fill information, and your dictionary. So it’s like a new Firefox with all your data already loaded.

Ex-Firefox Guy Says Remove Your Antivirus

This last tip is a controversial one. Former Firefox developer Robert O’Callahan says that your antivirus is why Firefox is running slow, and he recommends disabling it altogether. In a blog post, he explained how the antivirus affects performance and even slows down updates.

We don’t explicitly recommend this unless you think you can live without an antivirus. For most users, this is fraught with risk. In fact, we actually recommend that you make Firefox safer with security add-ons Completely Secure: 11 Must-Have Firefox Addons For Security Think about the browser you're using to view this article right now. Is it safe? Is it secure? You'd be surprised by those answers. Read More .

Image Credit: Albert999/Shutterstock

Related topics: Mozilla Firefox, Troubleshooting.

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  1. Art Bacon
    March 6, 2020 at 12:09 pm

    Disable AntiVirus? Are your Nucking Futs? I'm switching to Edge Chromium. This advice is simply insane.

  2. Wanda
    July 25, 2019 at 6:15 pm

    these tips have helped my firefox speed up . . . thanks

  3. Dave
    May 27, 2019 at 4:36 am

    This is no longer helpful.. none of these options exist in FF any longer

    • Yash Pal
      March 16, 2020 at 8:13 am

      Yes, they do not. Better take this page down.

  4. Oscar
    February 16, 2019 at 11:07 pm

    You forgot the fix which is 100% effective: Uninstall Firefox and choose another browser.

    • Related To Trump
      August 16, 2019 at 8:57 am

      How slow do you mean, do you mean your Idea of slow could be fast, or am i to slow to pick up on the idea it could be faster than the slower guy but its still slow.
      What do you mean slow crawling slow or you have that much junk on your Pc you need to reinstall slow is it you internet speed thats slow or is it when you load CNN pages explain How slow you are

  5. Jim Holley
    June 23, 2018 at 5:37 pm

    None of this worked and speedyfox is not compatible with my vs 60.x.x

  6. bennet nash
    December 22, 2017 at 4:09 pm

    Out of date, add-ons searches for "Speed Tweaks", "SpeedyFox" or variations on those strings don't work.

  7. JeanBon
    November 26, 2017 at 1:12 pm

    I just wonder for long now
    I've checked that after several months while FF is running good, FF begins to slow, crash, use tons of memory and/or process (Windows) and nothing does unless I update to the newer version and then, as a miracle FF is running fast and good for weeks or months.

    Question : does Mozilla uses a sort of remote system to force upgrading FF by provoking memory leaks and process use ?

    • kgbme
      March 14, 2018 at 6:48 pm

      Btw., on Windows, the Firefox profile folder is stored in %appdata% and the Profile Manager can be started with WinKey+R and typing from Run... firefox.exe -P

  8. mahibul
    October 5, 2017 at 10:42 am

    (function(d, s, id) {
    var js, fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) return;
    js = d.createElement(s); = id;
    js.src = "//";
    fjs.parentNode.insertBefore(js, fjs);
    }(document, 'script', 'facebook-jssdk'));

    • Bennet Nash
      December 22, 2017 at 3:58 pm

      No explanation of what this is, what it does, how to implement it. Completely useless post. Thanks for wasting our time.

      • uhclem
        November 7, 2018 at 10:25 pm

        I think it's code to add a Facebook "Like Button" magically into the comments.

  9. alex
    August 23, 2017 at 7:20 am

    Fire Fox is the most comfortable car on the highway. Not the fastest and not the most economical but it is so flexible and comfortable that for me it is the choice for 15 years. I tried others ... but I quickly returned home ... to the fox I know and cherish

  10. Ashton
    August 22, 2017 at 10:27 pm

    1. Install Vivaldi.
    2. Profit?

    • Bennet Nash
      December 22, 2017 at 4:00 pm

      No explanation of what Vivaldi is, where to find it, how to install it, how it fixes any problems, what problems it fixes. No explanation of what you mean by "Profit?"

      Completely useless post. Thanks for wasting our time.

      • Ashton
        December 22, 2017 at 4:32 pm

        It's a browser, it's been covered here before.

  11. fcd76218
    August 22, 2017 at 8:15 pm

    "Do you think O’Callahan is right about not needing an antivirus?"
    He's entitled to his opinion. I certainly will not uninstall my A/V and I don't even use Windows.

    "Are Firefox’s security add-ons enough to protect you?"
    They're better than nothing but the only way to be 100% protected is to be totally disconnected from the 'Net. Although even that may not be true any longer as there have been stories of 'air gapped' systems that have been compromised.

  12. 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

  13. Anonymous
    September 24, 2015 at 5:41 pm

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

  14. Anonymous
    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.

    • CodeLurker
      July 4, 2017 at 7:17 pm

      Turn off Automatic Updates!

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

    The second one worked for me, thanks!

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

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

    • Bennet Nash
      December 22, 2017 at 4:01 pm

      Which browser? List good browser substitutes for Firefox, how to find and install them, why they're better than Firefox.

      Otherwise, your post is a useless waste of our time.

      • Joe
        December 9, 2019 at 3:58 pm

        Would hate to have a 1 on 1 conversation with this guy. It would be a useless waste of time.

  17. 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.

  18. 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). 

  19. 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

  20. 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!

  21. 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

  22. 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

  23. 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.

  24. 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.

  25. 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.

  26. 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.