Firefox Community Forum

9/19/2026 Firefox Version 156.0 (64-bit) for windows 11 up to date with Windows Updates. I often have 2,3,4 Firefox windows open, each with several tabs open. Sometimes, Firefox will just totally freeze, and I can't do anything more. ALL Firefox open windows and tabs freeze. Other windows/apps are fine, and working normally. Only Firefox seems to be affected. The only thing I can do is use Windows to totally close/end the Firefox application. It then closes all the Firefox windows. I can then reopen Firefox, and everything seems fine - but I have totally lost the open windows and tabs I was on.

This has happened across several Firefox updates. I do not think this happened prior to 2026. Maybe just since June 2026.

One Extension - Web Threat Shield

Thanks!

MAC Platform:

             OS:   macOS Taho 26.5.1

Computer: MacBook Pro 16-inch 2021

                    Chip:  Apple M1 Pro (Silicon)
                    Memory:  32GB LPDDR5 (Hynix manufacturer)
                    Graphics:  Apple M1 Pro  GPU Built-In Bus, - 16 Total Cores, Vendor Apple, Metal Support: Metal 4
                    Model Identifier:  MacBookPro18,1
                   Model Number: Z14Z00109LL/A
                   Total Number of Cores:  10 (8 Performance and 2 Efficiency)
                   System Firmware & OS Loader Version:  18000.120.36
                   Activation Lock Status:  Enabled
                   Internal Storage:  SSD 4TB Capacity ;  File System APFS; Free 2.12 TB
FireFox for MAC:   Version 15.1.0.3 (aarch64)

Firefox MAC freezes intermittently , will get spinning beach ball and status shows Firefox (Not Responding) and must force quit FF.

Sometimes FF after fresh down load from the official FF site for MAC will work great for an hour or half a day and then out of now where go into the spinning beach ball , and unable to enter data into any field - completly bricked and FF status shown as Not Responding. Tnis could happen immediately, or after an hour or anytime within a day or two.

No way of deciphering or determining what in the heck triggers it or why - way way too many factors and settings and variables both within the FF registry and the macOS and the activity I may or may not be doing at any given time.

I will say I experienced this when all apps on my MAC were shutdown, no apps up and running, but I do use Backblaze, Mai Backup X, Malwarebytes, Dropbox, MS NTFS Tuxera, DriveDX which all have ongoing background tasks running all the time or at least in the background from time to time.

However, I have used this setup for the last few years with Firefox MAC with absolutely no hiccup whatsoever.

And then immediately after the last FirForx update on Tahoe, just before I applied the latest 16.5.1 Tahoe upgrade is the intermittant freezing with FF started.

Could this be a FF / Tahoe incompatibility issue?

If not, does anyone out there have anything to fix this?

And yes i did a complete uninstall of all of FF hidden Library folders as well as the "firefox.app" itself - if anyone tells me to uninstall all the hidden FF folders and files in ~/Library one more time, then forget it, I am done using FireFox. Been there and done there a number of times the last week, exhausted with that, and doesn't do a thing.

And yes kept deleting and creating new FF profiles and did not fix the issue.

So does some great genius Mozzilla FF Mac SW engineer have any clue as to the real issue and the real fix without sending me on a wild goose chase?

thank you. clb6

Hi, I’ve noticed that Firefox sometimes becomes noticeably slower after I’ve had it open for several hours, especially with multiple tabs.

Closing a few tabs helps temporarily, but I’d like to understand what is actually causing the slowdown rather than simply restarting the browser.

What would be the best way to identify whether the issue is related to an extension, memory usage, a particular tab, or Firefox itself?

I’m using the latest Firefox version. Any troubleshooting steps or tools you recommend would be appreciated.

I have version 156.0 (64 bit). It seems like the freezing started soon after the update and it is getting worse. Tonight it is only unfreezing for less than a minute. Some of the extensions showed that they needed permissions updated. Since I could not figure out what they did, I disabled them. None mentioned cursor control or issues that looked like they were nothing but options.

I started noticing that Firefox was giving me a lot of "not responding" freezes the past couple of weeks. The past couple of days I basically cannot access Firefox at all - constant, immediate freezing. I have tried uninstalling/reinstalling (multiple times), disabling hardware acceleration, running troubleshooter mode (still freezes! if it opens at all!), deleting profiles, restarting my computer, etc. I've done just about everything I can find online about this issue. Nothing has worked. I have no issues with Chrome or Edge.

Any suggestions??

Hi,

I have been using firefox for a while now and realised there is this annoying performance issue tied to my laptop, where firefox keeps freezing randomly while switching tabs or scrolling. It doesn't seem to happen on my desktop pc, and browser such as edge and chrome doesn't have this issue on my laptop, so I am confused as to what is causing it and how I can fix it.

My laptop specs are as follow: GPU - RTX 2000 Pro and intel arc 140T RAM - 64 GB LPDDR5 CPU - Intel core ultra 7 265H

Hello, Might the "do not sell" signal (that firefox offer to send automatically to website) slow the browsing please ? I can't figure out if it is a whole request to send in addition or just few bit more in the initial one, or something else I don't have in mind. I'm currently struggling with lots of tabs slowing my computer, even paralyzing the mouse . I try to optimize as I need to keep my tabs, but I don't what is the best way to manage that. Are the tabs less expansive than using windows, for the memory ? Could the groups of tabs lighten the storage ? Is it better (and more usable! ) to bookmark or add to "the task bar" when we just need to keep the adress to use it later ? Actually, is there a doc already answering to that please ?

I hope you might understand my bad english and that sometimes, we can't find other way than keeping too many tabs.

Thank you, Erin

Hi Mozilla team,

I’d like to report a serious issue with Firefox lately. The browser has been performing very poorly and frequently becomes “Not Responding.” In many cases, websites fail to load properly or get stuck indefinitely, even though my internet connection is working normally.

I’m experiencing these issues on the latest version of Windows 11 with the latest version of Firefox. This has become quite frustrating and significantly affects my daily browsing experience.

I hope the Firefox team can investigate these stability and website-loading issues and provide a fix soon. Firefox used to be much more reliable, but recently the overall experience has been very disappointing.

Thank you.

Hi,

Whenever I try to upload any sort of file, the file explorer pop up thing opens, and then freezes. This doesn't happen with any other application, just Firefox, and it happens across websites. Eventually the window freezes long enough that you get the 'close/wait to respond option', and then it closes. Firefox itself doesn't freeze, just the file picker. Nothing ever crashes/closes unexpectedly, and there's no crash reports in the about:crashes thing.

It's not super urgent because you can copy and paste most files but it is frustrating. Any help would be very appreciated.

Thank you

Ever since a recent update, my animated wallpaper for Firefox only plays one frame, and then freezes. If i switch or refresh tabs sometimes it can trigger the GIF to start playing normally, but 90% of the time the background stays frozen, I don't think this issue is related to my PC because the wallpaper was working fine before the Firefox update, and I'm having the exact same issue on my laptop too.

I’m experiencing a strange issue on Firefox where a separate blank/dark window briefly appears over the browser while I’m browsing, then disappears.

The window appears to have the Firefox icon in the top-left and what looks like a Firefox tab/address-bar interface, but there is no visible text or error message.

It happens randomly while Firefox is open, including while watching YouTube. It does not appear when Firefox is closed.

Troubleshooting already performed:

• Windows 11 cloud reinstall using Remove everything
• New Microsoft account
• Defender Offline scan clean
• Multiple malware scanners clean
• Malwarebytes Premium installed
• uBlock Origin (only extension i use) removed/tested, but the issue remained

I took a picture showing the window appearing. Is this a known Firefox issue, background Firefox process, or something else?

Hello there,

I realized that quite often when I restart Firefox (Developper Edition) and restore my previous session (latest occurence with 46 tabs), the window becomes invisible. It still exists, and I can even see it in the Window menu list pointing to my latest tab but it's nowhere on screen. I can add/navigate through/select/remove tabs using the keyboard, I can see them listed on screen when I Ctrl-Tab but the whole window remains invisible.

It'd be great if someone could help me out.

Best regards,

Emmanuel

I’ve noticed that Firefox gets noticeably slower the longer I leave it open. Pages that normally load quickly start taking several seconds, scrolling can become a little laggy, and sometimes a tab will just sit there before responding. Closing and reopening Firefox fixes it for a while, but the problem eventually comes back.

I’ve already tried clearing the cache and disabling a few extensions, but I still see the same thing. I usually have quite a few tabs open because of work and research.

Is there a setting or troubleshooting step I should check to figure out what is causing this?

When I login to Fidelity site, my username is displayed one letter at a time with noticeable delays. It started about 4 weeks ago. I noticed Remote Procedure Call was active with 4% CPU. I disabled remote access. The issue went away for 3 days, but has resumed today.

Is my FireFox hacked?

I changed browser to Microsoft Edge. The problem went away.

Hi, I am using Firefox For a few years, but for last 1 year my workload is high and I usually need to open several tabs. After I keep tabs open for a while, firefox becomes slow. Closing a few tabs help but I want to know what is causing it. IS there a way to check which tab or extension is causing it? I am using latest firefox on windows 11.