Firefox Community Forum

I am a Cacti developer and we are considering switching from FontAwesome Web Fonts to Tabler Web Fonts. However, on Firefox for Windows only, we are having a major slowdown when using the Tabler SVG based webfonts. The page load is first stalled by Firefox apparently loading all the Web Fonts, which would appear normal with any browser (though exceedingly slow on Firefox for some reason).

However, once the page is loaded, when going off tab to another browser tab, and then back to the Firefox tab that includes the Tabler webfonts, there is a 3 second delay before the tab switches. When we enable the performance analyzer, we find that the delay is almost 100% Reflow of the page, even though the page is static as this point (no changes) from the last time it was activated.

We do not have this issue on Firefox for Linux, MS Edge or any other Chromium browser, only Firefox on Windows. I'm using the latest version 134. Should I be opening a bug?

Using desktop 141.0, noticed issue of the hand pointer either not appearing, or appearing for less than a second and disappearing when hovering over buttons/urls/etc elements. Sometimes it stops being buggy for a minute or so and then goes back. I can't figure out the exact cause for this, but maybe going outside of the window of the browser ? Consistent in the safe mode, on different websites. See the gif for the visual

I downloaded Firefox not too long ago to combat the fact the Microsoft Edge wasn't working correctly, but ever since I downloaded Firefox it's been making my computer run really slow on the browser. Things are often slow like scrolling up on and down pages websites like Pinterest, and the text when typing on Google docs takes a moment to show up after I've typed it and not instantly, for example.

I checked my computer's task manager because I recently cleaned the laptop, thinking that something else was causing it to be slow, but it isn't. I don't have many processes open on the computer mainly mandatory things and my browser, since I use my laptop mainly for school work, music, or writing. Firefox opens multiple processes, the highest being 21 at one time, and takes up most of the memory on the laptop. Is this normal? Because it takes 1,094.0 MB and keeps my laptop's memory at 90-91%. If it isn't normal, how can I reduce this as well as the lag on my laptop when Firefox is open?

I attached a photo as well.

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!

Hello,

In the DevToolbox, the “Copy all as HAR” and “Create file...” functions are not working. It seems that in both cases, only empty space is placed in the clipboard and in the file (this has been happening since the last update).

Thank you in advance.

При заходе на сайте ya.ru и если на нём имеется строка с видео или поиск с алисой, то начинаются сильные фризы. Это ошибка именно в firefox 142, проверенно.

whenever i scroll trough a website in firefox, the ewperience is very laggy, feels like its 15fps. i have done basic things like disabling hardware acceleration, smooth smooth scrolling.

Hi, after latest update just now, the browsers uses up to 45gb of ram within a few minutes! Not sure what it is, I am on MACOS Sequia Version 15.6.1 (24G90) macbook pro M1

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.

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 brought Firefox up about a week ago, it presented me with a survey, results of which were sent to Firefox developers. They asked several multiple choice questions about features, but they didn't ask a very important question: Would you use Firefox more if it used less system memory? I currently use Google Chrome for about 2/3 of my web browsing because Firefox uses up too much system memory. I would prefer to use Firefox most of the time, but can't, since it bogs down when memory usage gets too high.

The survey should have included a text input box so users could enter any comments for the developers, and the survey did NOT do that.

So, after completing the survey, I was disappointed that I couldn't comment on the most important issue I have with Firefox. I would like the Firefox dev team to try get Firefox's use of system memory down. A short while ago, I opened 4 websites in Google Chrome, then opened the exact same 4 websites in Firefox. The attached shows the memory usage of each browser.

It seems that since the Version 141.0 update, initial startup of FF seems to take ve-e-e-ery long (approx 3-4 minutes).

The startup time/lag seems almost the same as it takes to restart after an update.

Anyone else experience this also? Thanks.

I normally use Firefox Developer Edition, version 127 because any later version always freezes my whole computer (probably because I'm using a 15-year old PC). Recently all my extensions became disabled. I'm now also unable to install any extension because it says "Installation aborted because the add-on appears to be corrupt". I found some instructions on Mozilla website about deleting compatibility.ini and extensions folder, but it didn't solve the issue. Now I'm stuck and confused as I suspect some of the extension files that should be in my Profile folder may not be there.

The simplest solution in this case would be to use the "Refresh Firefox" option which resets everything to default settings, but every time I do it my computer freezes until rebooted. Uninstalling and reinstalling manually is also not the way to go, because it retains all the settings.

I've tried installing the standard Firefox browser (v. 119) alongside the Developer Edition but the same issue is there as well.

I'm looking for an alternative way to get a clean Firefox install, so I can fix my extensions.

Additional info: - Your system specs? Windows 10 64-bit, 4 GB RAM, Pentium Dual-core, no GPU - Hardware acceleration? Disabled. - Using any mods? Yes, two. Geckium for Firefox, which always works fine. The recent issue started when I played around with Revert8Plus, but it initially worked without issues.

About two weeks ago, Firefox started randomly hanging and would stop responding. It wouldn't let me close the program and I always have to restart my system to resolve the problem. Sometimes it only takes a few minutes after restart before it hangs, other times it will be fine for hours.

I've tried multiple solutions I've found online, carefully following instructions: clearing cookies and cache, disabling all extensions, refreshing firefox, creating a new profile, deleting specific files within the Profiles folder, etc.

I've yet to make it more than four hours without the program hanging.

Any assistance or suggestions are greatly appreciated.

It takes almost a minute for my home page to come on after I click on My Firefox icon. That has only started happening in the last week or so. But . . . also . . . when I sign into my email account with my ID and complete password, even though I check the "stay signed in" box, that does not happen. I need to fully sign in each time, and that, too, time-wise is somehow related to the delay in getting my home page up. On several occasions I have gotten a message that Firefox is not responding. Thanks for any help you can give. I have Windows 11.

Firefox freezes when I try to sign into YouTube via Google. Becomes totally unresponsive and I have to close browser. It's the only site this happens on. I have cleared the cache and cookies, unchecked "Hardware Acceleration" and other recommendations from other posts. Please talk to me like I'm your Baby Boomer dad.

Using Google Voice became unusable. Firefox too slow. Had been running just fine up till maybe a month ago when I finally gave in and allowed Firefox to update. Not knowing if it was a Windows or other issue I stupidly did a Windows reset and lost all my installed programs (including Firefox). I did a fresh install of Firefox and manually reentered passwords and bookmarks.

Ran fine for a day or two and is now again unusable. Cleared cache and appears to work OK at the moment but still sluggish.

Finn

Hello For some reason most of the buttons in my toolbar have stopped working. When I first open Firefox they all work, then when I enter websites they stop working. The 'home' button still seems to work, but almost all others (such as the 'back' button etc) can't be selected. This is very frustrating. To note, I am not tech savvy at all.

Thank you in advance for your help.

Andrew

My Firefox desktop app recently updated. After it updated, I now cannot access anything by right clicking. When I right click, a giant window of options shows up (see image). It doesn't change no matter what I click on. When I try to select something in the giant window of options, nothing happens. I'm having a very hard time with it, particularly because I can't open links into new tabs now.

Hello, I used to use FireFox consistently. Then I noticed a downgrade in performance. I checked Task Master and saw this FireFox with 45 entries. With few CPU entries, but over 3 Gigabytes of Memory usage. Why would that be, and what can I do to correct it and still be able to use FireFox?