Firefox Community Forum

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'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

Unable to watch on YT ESL spirit v EF CS2 as memory usage constantly going up until pc almost locks up. Had this issue a few weeks back and it was the chat however now disabling chat makes no difference.

Nm tried disabling Ublock origin and it's fixed, left this there as it might be useful to you guys

I can only use firefox for 90 minutes at a time, before the entire system crashes.

Since the last couple of updates, the infamous memory leak issue has gotten significantly worse. Now 30 minutes of use with no add-ons sees the memory use swell to 13 GB, crashing the system. Sometimes windows 10 crashes, sometimes it just kills firefox.

The thing is, when I check about:memory, it says firefox is only using 1.5 GB. However task manager says 13 GB, and if I close the browser, suddenly 13 GB memory gets freed up.

Does anyone have any idea why there's such a discrepancy?

Hi, I use Firefox all the time, love it. But I have noticed a problem.

If I have say 7 tabs open, none of them doing anything, then go away from my laptop for say 20 minutes, when I come back the fans on the laptop are screaming. Even if it was minimise.

I have a fairly modern laptop Dell GSeries1522, 12th gen processor, 16gb ram, i7.

I have tested this issue using Edge and Chrome with exactly the same tabs open and the laptop is all quiet. I'm on the precipice of moving to Edge. Happy to provide more information. Task Manager now shows FF using 1223.0mb of memory, Edge 466.7mb. They are both in "efficiency mode".

Any help or advice would be great.

Peter Hall Brisbane, Australia.

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!

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

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.

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?

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.

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?

My firefox is using up too much memory, up to 60% of my laptops memory, even when I am not using youtube. and I can't figure out what is causing it to use so much. I've used minimize memory to no effect, can you figure out what is causing it? This link has a memory report to help

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!

Доброе время суток!

это папка C:\Users\Илья\AppData\Roaming\Mozilla\Firefox\Profiles\v2zudvil.default-release\storage\to-be-removed постоянно растет, удалять ее приходится вручную, почему так происходит? и как это избежать 

последний раз, когда удалял, это папка занимала 52ГБ

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 use Firefox 134.0.2 (aarch64) as my primary web browser. I only have it open 15 minutes and I am receiving alerts that my RAM memory is being consumed by it. I am using a Mac Mini Pro M2 chip with 32GB of RAM . I have just opened Firefox to discover it is taking 10GB of that RAM. It is the most voracious user. If I have it open longer it gets up to 16GB of memory. I often have 5 or 6 tabs open when I am working. My other browser is Chrome that barely makes it to 1GB

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.

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?