I-Firefox Community Forum

I have a HUGE problem with Firefox memory usage. Some open instances of firefox are taking anywhere from 600mb to 2.8gb of memory. Since firefox opens MANY instances even with only ONE active window, this very quickly uses all available memory (4gb) causing a full laptop crash.

More concerning is that CLOSING the worst instance of memory usage STILL leaves the single open page/tab open, so what exactly was the memory eating instance actually doing ???

I have included a screengrab of the many remaining instances of firefox in windows task manager AFTER closing the main culprit.

I have also included a screengrab of all the adblockers I use which I believed would limit unnecessary memory usage, but does not seem to be effective.

Many Thanks

I’ve noticed that Firefox consumes a lot of memory, especially when I have multiple tabs open. Sometimes, it slows down my entire system, and Task Manager shows Firefox using over 1GB of RAM even with just a few tabs. Other browsers like Chrome or Edge seem to handle memory better with the same number of tabs.

I’ve tried restarting Firefox, closing unused tabs, and disabling a few extensions, but the problem keeps coming back. I even checked techsquest.com for tips, but I’m still struggling. Are there specific settings, hidden features, or optimizations I can apply to reduce Firefox’s memory usage without sacrificing performance?

Here’s what I’ve already checked:

Firefox is updated to the latest version.

No unusual extensions running (just uBlock Origin and Dark Reader).

Hardware acceleration is enabled.

Any help would be appreciated—thanks in advance!

Please assist or advise why Firefox seems to be slowing down my system by memory usage. I have a handful (6) of tabs open on 1 browser session and my system started slowing down so I checked my task manager and it shows that I have more than a dozen of Firefox instances open chewing up almost 90% of my memory.

Please assist or advise me on how to tweak my browser to perform better, and not to show ghost instances

I have two Firefox tabs open on my browser. Task manager shows 35 tabs using 897 MB of memory. How do I make this stop? And why are so many tabs running? I have cleared cache, cookies, etc.

I'm tired of trying to find a solution to this problem, you're deaf!

I have been using Firefox since 2003. to avoid writing unnecessary words, I will simply state, I will leave firefox if you do not eliminate this problem:

firefox eats up all the RAM on my Mac. It is none of your business whether I open 1 tab or 10 tabs, give me the ability to limit the memory used by firefox, otherwise it eats up all the computer's memory.

Is this a bug or config problem?

Occasionally, FF (Linux desktop) starts using a lot of memory. I kill tabs (sometimes it is OK to kill YouTube or X, sometimes not)

Eventually it starts impacting the system using so much memory. I terminate the FF instance. Often. More often than not. There is a separate task still running and I get the "Firefox is still running" when I try to restart. I then kill the remaining FF task via the OS or the process monitor. Then FF restarts.

Is this an issue with addons (I am running very few - uBlock Orign, and Privacy Badger and Cookie AutoDelete. Are the only ones active most of the time) Or is it an actual bug with garbage collection, and tasks getting away? Or is it an OS issue?

Lately, I’ve noticed Firefox consuming more RAM, especially with multiple tabs open. Is this a common issue in recent updates? What are some tips to optimize Firefox performance on lower-end PCs? Would love to hear your experiences!

For some weeks I have ad an issue with Firefox using 50%-100% of CPU. Normally it is the Firefox process itself, sometimes it is also "Privileged Cont".

OS is Kubuntu 24.04. Firefox has done this across 2-3 versions.

Things I have tried:

Restarting Firefox No change, I'll even get 100% cpu usage with no tabs open

Refresh Firefox to remove settings and addons No change

Uninstall Snap and try direct Apt package No change

Remove ~/.mozilla to fully remove any residual settings/cache/etc No change

Try with and without hardware acceleration See: https://support.mozilla.org/en-US/questions/1308215 No change!

I would blame my old computer hardware, but Brave runs fine. I am now using Brave, but would dearly like to return to Firefox as I miss containers, and I don't support a chromium dominated web.

I believe this problem began in 133. I've noticed that if FF is open for a few hours, it starts to develop a very noticeable input lag. For example, if I'm watching a YouTube video and hit an arrow key to advance the video, there will be a couple of seconds before the browser registers the key press. It behaves like a high CPU issue but I do not detect high CPU usage when this is happening. Restarting the browser resolves the issue for a few hours.

This is happening on Windows 11 as well as on a Mac running Sonoma.

I am a heavy Firefox user, and have been using it (and its predecessor) since Netscape. In the last year, the size of my Firefox profile has more than doubled, from 500MB to 1.3GB. What's the probable cause(s), and what can I do about it?

Hi, after update 137.0.1 (64-bit) using Firefox with latest Gecko driver 0.36.0 in Python Selenium stalls and fails to initiate drivers without returning initiation errors every second launch, previously this stall without returning initiation errors would happen every ~25th launch. Also when it does successfully launches previously 9 instances used to use about 95% of my 8 GB RAM, now 6 instances use 100% RAM. Nothing else in my system changed besides Firefox update.

I'm finding that firefoxcp isolated web content uses a LOT of memory on my Mac Mini. What can I do about this besides not using Firefox. I like the browser and have been using it since its introduction

When I open one tab on Firefox, my task manager shows multiple programs running along side it. I know some extra processes are needed but this seems like an unusual amount. I have included a screenshot of the tasks that appear. When I try to delete these, they reappear. I have tried various online solutions such as uninstalling and reinstalling, and checking various settings. It is affecting my computer's performance and I am not sure how to solve this. Thank you!

I've noticed my GPU fan runs heavily as soon as I open Firefox, and with even just only one browser page open, it runs high speed, where it didn't use to do this. How can I get Firefox from requiring so much of my power. I don't want my electric bill higher just because of a browser. I have a decent GPU good for gaming quality that usually doesn't get clocked enough to cause the fan to turn on and run at high speed unless it's a high-graphics computer game or something. Anything I can do to make the browser demand less on my GPU?

There is a similar (but not identical) topic on Mozilla Connect , and I posted there. But I did not get a response. So I am re-posting on this new topic on Mozilla Support. I have a similar problem to what was discussed on Connect. I am using Firefox 133.0.3 on Windows 10 Professional. After Firefox has been running for a while, I get a message from Windows 10 that the free space on my C:drive is low. I did a directory listing on my C-drive before and after Exiting Firefox; I saw no large files disappearing. Then I decided to do "dir c:\ /ah" to see hidden files. What I saw was that pagefile.sys decreased in size from 29,925,748,736 to 16,270,770,176. This was a decrease of 13.7 Gb. Is this normal? I have lots of windows and tabs open in Firefox. Thanks.

Firefox is creating very high CPU use with many WebThumbnailExtension Web Connect processes. The processes disappear after shutting down Firefox and other programs that access the internet. Does anyone have an answer on how to prevent this from happening?

MacBook Pro M4 with MacOS Sequoia 15.3.1