I-Firefox Community Forum

I am on a Mac desktop running Ventura 13.7.3 and running Firefox 135 with extension of Ghostery, Privacy Badger, Google Don't Track Me, Facebook Container, FoxClocks and SoftGreenLeaves theme. All of these extensions have been playing nicely with each other for a long time.

Recently I've been having trouble recently with Firefox doing that thing of suddenly freezing/producing multiple windows and I need to refresh in order to get it working properly again. This has happened three times in the last five days - so frequently that I now keep the refresh instructions on my desktop. Today I heard the CPU grinding and clicked open my Activity Monitor to see four listings of 'FirefoxCP Isolated Web Content' running all of them using in excess of 2Gb. Unfortunately I wasn't able to get a screenshot of the Activity Monitor while this was going on as I had the Mac force quite Firefox and the moment I did, the activity stopped, but I've attached an example of the Activity Monitor showing still high CPU values for a few moments of browsing.

So what's up? How can I stop the CPU grab? How can I stop the frequent crashing?

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'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.

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?

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.

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

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!

All of a sudden, I get a "Not enough room to save" error message when I try to download a fill. There is plenty of room on my disk.

Also, it's not giving me the option of just opening the file.

I've been needing to use Edge to download files.

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.

Has anyone else noticed that the memory leak issues have gotten way worse since last update?

I work on a potato. Most of the memory is in the windows paging file, on a mechanical hard drive. So freeing up used memory takes longer than it would on a machine with a metric tonne of quad-channel RAM. The past 6 months, Firefox has started having memory leak issues, where it just uses more & more memory until the paging file hits its hard limit and windows kills firefox.

But since last update (135.0 x64), the memory leak issue has worsened significantly.

If I open firefox, and then tab between all current tabs, I get maybe 5 GB of memory usage. So even if all tabs are marked as "active" and loaded into memory, this still isn't enough to cause issues.

But after 30 minutes, that memory usage has ballooned up to >20 GB, at which point windows decides that it needs to free up memory, and kills the process. Which is annoying, because then the browser reverts to the last saved state, meaning many tabs can be lost or reset to several clicks back.

I've tried shaving off extensions, with zero change. I've tried increasing paging file size, but that's just kicking the bucket down the road.

Anyone have a solution to this?

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?

About once a minute or more Firefox lag by 10-15 seconds before showing a character or characters I have typed.

It seems to be using a lot RAM. I have one window open with six tabs, including this one, and it is using nearly 8GB. There are 48 processes showing in Activity monitor.

I am using version 135 on a Mac Book Pro running MacOS 15.3 (Sequoia).

It is almost unusable.

Since around the time I updated to Windows 11 version 24H2 (which I severely regret doing, but it's too late to revert), my computer runs very slowly for several seconds whenever Firefox is launched or whenever its window is restored from minimized. It also randomly slows down the computer every minute or two for several seconds. The slow down manifests as a very long lag in cursor movements and typing.

The impact is most severe when I am running other programs at the same time, including Outlook and a rather old version of Quicken, but it can be seen even when there are no other programs running.

This happens even in Firefox troubleshoot mode. This happens even after a refresh. I tried deleting my entire Firefox profile. I tried uninstalling Firefox and reinstalling it. I tried reinstalling the two previous versions of Firefox. I tried with hardware acceleration off and on. I tried changing every possible video setting I could find. My video drivers are fully up-to-date, as are my Windows updates and my BIOS. Nothing has helped. The same problem even exists with a brand-new installation of Firefox and a brand-new profile!

Notably, I don't see this issue with either Chrome or Edge. And I don't see it when many other programs are running at the same time without FF, even RAM-hungry and CPU-intensive programs like image and video editing programs. This is specifically a FF issue.

Before updating to Win 11 ver 24H2, FF was running on this computer for years without issues. I can't say the problem started exactly when I installed 24H2, but it seems like it was around then. I have another computer still on 23H2 with the same version of Firefox (and the same versions of Outlook and Quicken) that does not have this issue.

My computer is essentially unusable when Firefox and any other major program are running at the same time. I've tried seeing if the CPU or RAM usage spikes during the slowdown, but since the computer nearly (but not quite) freezes when it happens, I haven't been able to catch it live.

Thank you to anyone who might be able to help. I've had to move to Chrome because of this, and I'm not happy about that.

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.

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.

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 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