Firefox Community Forum

This started happening a few days ago.

I tried to drag a tab out of the main window to put it in its own window on my other monitor, but the tab just became unselectable, and if i scrolled in the tab bar, the tab icon and text would remain locked in place in the display while the other tabs moved behind it.

The main Firefox window also lost the minimize, restore, and close buttons. The only way to make the tabs work was to close Firefox and relaunch it.

I noticed this happened only after any app in the OS went full screen, be it a steam game, or another Firefox window, or a VLC window, or anything else that I did that made an app full screen in any of my monitors.

I am using Ubuntu 24.04 with KDE Plasma 5.27.12. Kernel is 6.14.0-29. Display server is Wayland.

Initially I thought this could be a problem with the snap version of Firefox, so now I've installed the deb package, but the problem remains. Firefox is the only app which presents a problem of any kind when any window goes full screen.

Here's a video showing what the problem looks like, in case my description was not clear. The ghostly tab in this video is the chess.com home page and you can see it as the third tab from the top right of the video, and it remains in that position as i scroll the other tabs, completely unselectable with the mouse.

https://www.youtube.com/watch?v=-mAfPS3_qkg

Any idea of what could be causing this issue to appear?

Thank you!

Ubuntu - I use the SNAP version of Firefox - I generally have lots of tabs open but only use 5 or so of them and it's generally fine.... but when I am closing Firefox, it USES like 100% of the CPU and ALL of the RAM and ALL of the SWAP memory when closing.

This locks up the computer.

Sometimes it doesn't quite go all the way but I can watch it all happen in real time, using Task Manager - and that shows a solidwall of all resources occouring, when the close Firefox is run.

I am told by research via ChatGPT that this is a very real problem with the SNAP version and it's best to change to the Debian version, copy all the bookmarks etc., across and then uninstall the SNAP version.

It's rather disconcerting to have Linux crash because of this one app locking it up and frequently.

Chat GPT:

Is there a problem with Firefox Snap Version closing and using all the resources while doing so, which results in locking up the computer?

You're definitely not imagining it—there have been reports of Firefox's Snap version consuming excessive system resources (CPU, memory) and even causing lockups or hangs, particularly during closure. Here's what’s going on and how to mitigate it:

What’s Happening with Firefox Snap?

2. Browser Hangs or Locks the System on Close

On Linux (especially Ubuntu), users have reported that closing Firefox can lead to it hanging in memory, sometimes unresponsive and still consuming resources.
Super User
Ask Ubuntu
A stark example from Reddit illustrates the severity:
“About 50% of the time I open Firefox, it'll reach 100% CPU usage in about 30 seconds… PC completely unusable unless I shutdown.”
Reddit

3. Known Wayland Sway Bug

On Wayland/Sway setups, reloading Sway while Firefox is open can trigger intense logging, causing high CPU use and an enormous syslog.
Fix: Set MOZ_DISABLE_WAYLAND_PROXY=1, or upgrade to FF 125 where the issue is addressed.
Reddit+1

Alternative Approach

Many users, particularly on Ubuntu, opt out of Snap completely in favor of the .deb package or PPA builds. These alternatives often avoid these specific issues. Ask Ubuntu Reddit

Thoughts? Solutions?

Thanks in advance.

When I have multiple tabs open, around the 6th tab, the entire computer freezes. I have to press the physical button to shut down and restart. This behavior started with the last Firefox update. It doesn't happen when I use Brave browser. What changed to cause this?

I'm running Mozilla Firefox for Linux Mint mint 100 - 1.0 version 141.0.3 (64 bit) on Linux Mint 22.1 Cinnamon. These are the latest versions of Mint and of Firefox for Mint.

Anyway to fix the issue?

Name: Firefox Version: 150.0.1 Build ID: 20260427221700 Distribution ID: canonical-002 User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:150.0) Gecko/20100101 Firefox/150.0 OS: Linux 6.8.0-111-generic #111~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Apr 14 17:13:45 UTC OS Theme: Yaru / Yaru Multiprocess Windows: 1/1 Fission Windows: 1/1 Enabled by default Remote Processes: 11 Enterprise Policies: Inactive Google Location Service Key: Found Google Safebrowsing Key: Found Mozilla Location Service Key: Missing Safe Mode: false Memory Size (RAM): 31.1 GB Disk Space Available: 383 GB

FIREFOX ... MMMMMMMMMMMMMMMMOOOOOOOOOOOOOOOOORRRRRRRRREEEEEEEEEEE THAN 16 GIGABYTES WITH ONLY 4 TABS OPENED. AND OF COURSE .... BROWSER FREEZES, NEED TO KILL FIREFOX TO STAR WORKING AGAIN ....

WHAT ARE YOU SMOKING THESE DAYS?

Arch Linux Wayland FF v150 from Arch repos

When right clicking the context menu appears, but sometimes in odd places, and the disappears, so you can't select anything.

Same is true selecting the Help submenu from the Hamburger menu.

Restarting the browser fixes it for a few minutes, then same problem comes back.

Other people also reporting the same thing - also Linux Wayland: https://www.reddit.com/r/firefox/comments/1suounc/comment/oi7jk9u/

I'm using Firefox 141.0 on OpenSuse Tumbleweed with KDE and Wayland. I'm using Firefox with two profiles: work and personal - which is (usually) awesome, until suddenly it's not.

Then, one or both profiles seem to become corrupted, and closing firefox, opening it, choosing either profile just hangs forever. My old tabs show up, but clicking on any tab, for any site, just hangs forever, and no page is ever loaded. Sometimes restarting helps, but sometimes not. Sometimes restarting 2 or 3 times and then suddenly it will work. But normally, I have to just delete all my profiles, and re-create them. Fortunately everything is synced with Firefox sync. Then everything will work wonderfully for a bit - although I have to re-login to everything.  :-(

Any ideas? This is a huge pain and productivity killer. I really love firefox, but this sucks.

On updating to linux mint 22.3 - cannot type anything in firefox in address box, search and primary password or anywhere else within firefox - have uninstalled & reinstalled but nothing happens

Firefox dropdowns, menus and popup menus do not appear after resume from suspend on Ubuntu 22 or 24 This has been happening for only the last few weeks. Even dropdowns on web pages do not appear. I can click the dropdown and cursor down then hit ENTER to change a dropdown's value but I cannot see anything while I'm doing it. On the menus, I can use hotkeys if I remember them but the menus themselves do not appear. Right-clicking to get a context menu also does nothing but it behaves like it did. If I right click something, nothing changes on screen but if I then click another link or button, the first click is swallowed to dismiss the non-existent popup.

Other apps on the system work fine including Chromium browser.

This only occurs if I start Firefox then suspend the machine and then resume from suspend. After resume, the menus, dropdowns and popups no longer appear.

I am running Ubuntu 24.04.4 LTS on a Dell Optiplex 3050, Core i3-7100x4 , 16 GB ram, Intel HD graphics 630 (KBL GT2), Gnome 46, Wayland windowing system.

I tried Firefox safe mode, clearing the caches, etc. Nothing worked.

Since a while, I think it is since I created an extra testprofile with "firefox-esr -P", but I've set my main profile as default again

When opening a link in another program than firefox I get always: a popup "Close Firefox" "Firefox is already running, but is not responding. To use Firefox, you must first close the existing Firefox process, restart your device, or use a different profile."

I do have both firefox and firefox esr, I usually use regular firefox the second came with the debian 13 repository.

I keep the esr to test display issues for reproducibility on my personal desktop, because I manage debian 13 kiosk-style desktops with firefox-esr.

(I noticed also that the regular firefox profiles can not be opened in firefox esr, so I use an extra profile for esr)

My Dell Precision Laptop from 2019 runs a frequently updated Ubuntu 24.04. About one or two weeks ago, after one of the latest Firefox updates, i noticed that video streaming produces rectangular flickering in rapid sweeps. ( Also fast scrolling large text websites produces similar flickering, I think I would have noticed it before...) . If you detected it once, you see it always again... :-( First I fiddled around with the nvidia settings because the driver was also recently updated, without much success. Playing locally stored videos, e.g. with VLC media player, still works fine, so the nvidia driver is not the problem i think. Yesterday I installed Chromium and the video performance is fine! As good as with firefox some weeks ago! So it must be one of the latest updates, that causes the problem. Generally I like firefox more than chromium. I like the control you have, e.g. via Add ons.. So I hope that the firefox performance will increase again... Thank you for firefox! Florian Mengedoht

• • Background:**

I'm a senior software engineer running Firefox Developer Edition on a Linux machine with 8GB RAM. I have Fission architecture (site isolation) enabled, which I understand is now the default since Firefox 95+.

• • The problem:**

When I open 20 or more tabs across different domains, Firefox's memory consumption scales dramatically — often reaching 4–6GB of RAM for what should be lightweight browsing sessions. This is significantly higher than what I observed before Fission was enabled.

• • What I've already tried:**

- Disabled hardware acceleration → no significant improvement - Set browser.tabs.unloadOnLowMemory to true → partial relief

 but tabs reload constantly, disrupting workflow

- Reduced content.notify.interval → marginal improvement - Tested with all extensions disabled (safe mode) → RAM usage

 still high, confirming it's not extension-related

- Checked about:memory → large number of separate

 "Web Content" processes, one per origin as expected with Fission

• • What I'm trying to understand:**

1. Is there a way to set a maximum process count cap for Fission

  without fully disabling site isolation? I found 
  dom.ipc.processCount but changing it doesn't seem to affect 
  Fission's per-origin process spawning behavior.

2. Is browser.tabs.min-warm-process-count a relevant setting here

  and what is the safe range to modify it?

3. Does Firefox have a built-in memory pressure threshold where

  it automatically consolidates processes — similar to Chrome's 
  memory saver — and if so, which about:config keys control it?

• • Environment:**

- Firefox Developer Edition 151.0b10 - OS: Ubuntu 24.04 LTS - RAM: 8GB - Fission enabled: confirmed via about:support - Extensions: disabled for testing

Hello! Today I stuck with problem in my system: after minor package update, hardware acceleration was broke. In past, I stuck with same problem after total pc upgrade (AMD -> NVIDIA GPU, another might be unnecesary), and somehow I fixed it, but i dont remember what exactly fixed it. Can someone please help me turn hardware acceleration on this time? My searching the key arround didn`t helped, but i found in about:support line which notes that firefox unrecognized my videocard etc. My specs: kernel: 6.17.1-zen1-1-zen driver: nvidia-dkms-580.95.05-1 videocard: GTX 1080 TI DE: gnome 49 with Wayland

Tips that ive tried: Tried to make all as wrote in archwiki Tried to install an nvidia vaapi implementor Made some random steps from internet, without effect(maybe thats why hardware acceleration doesent work??)

theres also about:support page attached

I updated firefox just yesterday or earlier today idk and the right click menu is so long with multiples of the same and they DO NoThInG! Linux Mint 22 Cin. 6.8.0-55 Generic Kernel

I recently upgraded from Ubuntu 24.04 to 26.04, using Mate Desktop and Compiz compositor. I am using Firefox from the Mozilla Team PPA, currently 150.0.1. I am running custom kernel built from upstream source, currently 6.18.25. Hardware is a home brew CoffeeLake machine, i7-9700k, 64G of RAM, 2TB WD Black SSD and many TB's of spinning rust, graphics is Intel ARC B50 Pro, ASUS XONAR SE 5.1 Channel 192kHz/24-bit Hi-Res 116dB SNR PCIe Gaming Sound Card. Prior to upgrading Firefox was not 100% occasionally tabs would wedge, now if I get two hours I'm doing good, I've tried disabling extensions and plugins no help. Tried with and without hardware decoding, worse without but bad no matter. Any suggestions how to get stability back?