Interesting.... Here is what I have in Win11 with 59 tabs and 11 add-ons. see screenshot Let me see what my mac running 10.13.6 is showing.

Here is what I see on my mac with more tabs open and the same add-ons. I would disable Norton, reboot, and run Firefox in Safe Mode to test.

Thanks for taking the time to look into this.

I am sorry but I would not know how to "disable" (and then enable) Norton. Also I know nothing about Safe Mode, etc. If I would get myself in trouble by doing things I don't know about I would not know how to fix them. Even if I would be able to do what you suggested, that might not be a solution to the problem and unfortunately I am less than qualified to do debugging.

A search on the web brings up many entries like the one below without an apparent solution, so this doesn't seem to be a unique problem. I didn't experience it until now and some appear to experience it, others no. If this is a known bug, then I just have to learn to live with it or switch to another browser. That's why I asked the question about this being a known bug.

https://connect.mozilla.org/t5/discussions/quot-firefoxcp-isolated-web-content-quot-is-slowly-consuming-all/m-p/1872

Thanks again.

See:

• https://www.google.com/search?sa=N&num=100&q=%22system%20has%20run%20out%20of%20application%20memory%22

Thanks. It seems that Firefox might be the application that causes the problem based on what the Activity Monitor shows. If I quit Firefox and the log back on (with the exact same websites open), the application memory used by Firefox is for a while considerably less than before.

I attached with the initial message a capture of what Firefox was using at that time.

Is it "normal" and to be expected for Firefox to have 30 entries open for FirefoxCP Isolated Content (with 7 apps open) and for Firefox to release most of that memory after quitting?

I asked if this is a known bug or not to know how to deal with this problem.

I am attaching 3 files after Firefox just crashed and I had to reboot the computer. Prior to the crash Activity Monitor showed 32 open FirefoxCP Isolated Web Content processes and 14.2 GB memory used out of total physical memory of 16 BG available memory with 11 tabs open.

The 3 files show memory usage from Activity Monitor after the reboot before Firefox was open, after Firefox was open and a capture all the Firefox processes after the restart (not in this exact order).

It is obvious that Firefox progressively eats up memory until everything comes to a screeching halt and Firefox crashes. Can someone who knows how to look up the bug logs at least tell me if this is a known bug ? It didn't happen until recently and nothing new was loaded on my computer. I have doubts that this is how it should work. Thank you.

Does any moderator have an answer about this? It keeps happening and by now I have to reboot my computer many times a day. Is this currently something happening only to me? Is it my computer?

I'd appreciate an answer.

I kept hoping that with the latest version the problem I am experiencing on my Mac will be finally fixed. It was not. The number of growing instances of Firefox Isolated Web Content that Firefox creates slows down or crashes the computer. I already attached screen captures and I asked multiple times if this is a known bug (as it apparently happens to others too) but it seems to be impossible to get an answer. Nobody really knows ?

I am attaching another screen capture and who know maybe someone will pay attention to this post.

Can at least someone tell me if what I am experiencing is only my problem and if this is normal? My posts have been all ignored. I am wondering why... I posted 3 captures from the Activity Monitor.

The best way to avoid seeing the error message is to make sure you keep as much memory as possible free on your Mac. An Apple-notarized Mac app, CleanMyMac X, has a handy Menu that makes it easy to monitor application memory and free it up anytime you feel like your Mac slows down. Here's how to use it:

   Download CleanMyMac X for free here. 
   Install and launch the app.
   Go to your menu bar and click the CleanMyMac X icon.
   Click Memory.

Regards, Jimmy

It is quite normal to see more Firefox processes running.

• process for the main Firefox thread (user interface)
• one or more content processes
  you see more content processes when Fission is enabled
• process for the compositor thread
• process for extensions
• process for WebRender when this feature is enabled

There are several toolkit.aboutProcesses prefs on the about:config page to show more info. You can find the current multi-process state on the Troubleshooting Information page (about:support).

• "Help -> Troubleshooting Information"
  "Application Basics":<be>Multiprocess Windows and Fission Windows
  "Remote Processes" (Web Content)

You can check the about:memory and about:processes pages for info about all processes. See also the about:unloads page for info about the tabs.

Fission:

• https://hacks.mozilla.org/2021/05/introducing-firefox-new-site-isolation-security-architecture/

Thanks Jimmy and Cor-el.

Since I have not loaded anything new or upgraded anything else on my computer other than Firefox for at least 1 year and I didn't have this problem before, I am still wondering if this issue was introduced by one of Firefox' releases. Is it "normal" to have 50+ instances of FirefoxCP Isolated Web Content with 15 tabs open? Why are they so many and why is their number increasing? I would appreciate an answer to this in layman's terms.

Would CleanMyMac X remove in the background the many instances of FirefoxCP Isolated Web Content, as these are the ones that chew up the memory?

Cor-el, I know that you are a technical expert. Unfortunately I am not. Unless Fission was installed and enabled by default by the Firefox install, I know nothing about it and didn't do anything about it. I am wondering how checking information about processes would help me. What could I do about the 50+ instances knowing what Troubleshooting would show? Isn't what Activity Monitor shows (the 50+ instances of FirefoxCP Isolated Web Content) saying something?

Maybe check the about:processes and about:unloads pages.

OK, I did what you suggested (looked at about:processes) but I have no idea how this is helpful for me. Just as an FYI I attached parts of what I see . I could not locate about:unloads pages, but probably it doesn't matter because without technical know-how one cannot do anything with this info.

Why cannot someone on this forum just answer my simple questions instead of talking about all kids of other things that do not address them?:

Is it "normal" to have 50+ instances of FirefoxCP Isolated Web Content with 15 tabs open? Why are they so many and why is their number increasing? Am I the only person experiencing this?

I would really appreciate answers to what I am asking about.

You are not the only user having issues with computer memory. The about:memory page has a button to minimise memory usage and several presses of that button do work for me.

Another thing that works usually is closing a tab which is using a lot of memory. You can open it again from History > Recently closed tabs. To see what is using memory open Firefox's Task Manager (from Tools > Browser tools in the menu bar OR More tools in the 3 bar menu OR about:performance).

Fission (now being described as isolated web content) is the default behaviour. You can switch it off from about:config. Make fission.autostart false. That won't necessarily help.

https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Thanks, Terry. I did what you suggested (about: memory) and will see if it helps. Firefox, Google syndication and xfinity.com are using the most memory.

I do understand that I am not the only user who in a generic way has issues with memory usage, but what I keep asking about is a very specific question about number of instances of FirefoxCP Isolated Web Content. Every Firefox user can see how many instances they have in Activity Monitor on Apple or some similar application on Windows. Why is that nobody can provide a direct answer to this question?

It's normal to see many instances (more than you would expect). Is that the specific question?

My question was in bold and italics in the prior message. Does anyone know if more than 50 instances of FirefoxCP Isolated Web Content are "normal"? Their number just keeps growing. Is that to be expected and normal? It was not happening in the past with somewhat older Firefox releases. Thanks

This had to be an unacknowledged bug, what was happening was NOT "normal". The 107 update fixed it. Since this update, the problem I reported no longer happens. Hopefully it will stay this way.