Does it still happen in Troubleshoot Mode?

Unfortunately, I just restarted Firefox in Troubleshoot mode and the RAM usage still/continues to increase.

You can check the about:memory and about:processes pages for info about all processes. There are several toolkit.aboutProcesses prefs in about:config to show more info. See also the about:unloads page for info about the tabs.

• https://Firefox-source-docs.mozilla.org/browser/tabunloader/

Does this happen on any site in particular?

You can visit about:processes in the address bar (Shift+Esc) to see which process is responsible.

No site in particular. In fact I closed all of my (5 or 6) tabs and the RAM usage continues to increase (I have 5-10 minutes before it hits 30-40GB; I have a lot of RAM for photo processing). It does not appear to be a process? It is the first line in processes, labeled Firefox, that continues to increase. All the other lines stay essentially the same.

Do you think uninstalling and reinstalling would resolve? That's what I am thinking. Since nothing else apparent/obvious, troubleshooting mode didn't resolve, etc., would seem more time-effective.

As I mentioned above FF has crashed numerous times the past couple of months and the crash reports are sent. Recently more frequently and quicker (so that I keep FF down unless I really need it; or access via my laptop). Maybe not logged/tallied by user?

Thanks.

Firefox has a built-in Task Manager page -- Shift+Esc or about:processes.

In the Windows Task Manager, click over to the Details tab to see the Process ID numbers for each firefox.exe process, to compare between Windows and Firefox's lists. Is there a major discrepancy, or can you see the same memory usage on Firefox's list?

(Sometimes there is a discrepancy because malware is running a hidden instance of Firefox for coin mining or other compute-intensive task.)

I looked at RAM usage in Task Manager details and compared to the about:processes and they line up/agree.

Does Firefox associate the process with the large memory footprint with a particular function, such as GPU or a website?

It appears to be the main Firefox app. On process manager (under Firefox browser), the first line item is Firefox - which is where the RAM increase shows up. Then the following lines are the tabsm about, extensions, GPU, etc. These following line appear stable in RAM usage.

Hmm, what could it be doing?!

You could consider removing and replacing the program files (a so-called Clean Reinstall). This doesn't involve removing any data/profile folders.

Step 1: Verify your program location

The Troubleshooting Information page has a row for Application Binary showing where Firefox is installed. On 64-bit Windows, this typically is C:\Program Files\Mozilla Firefox\ but on much older installations, it might be under C:\Program Files (x86)\Mozilla Firefox\. (Use the Troubleshooting Information page to help fix Firefox issues)

If you installed Firefox from the Microsoft store, it would be somewhere obscure and this procedure is not applicable.

Step 2: Download a fresh installer from https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Step 3: If you use an older version of the Microsoft Office suite on your computer, removing the folder can cause Office to freak out a bit. As long as we reinstall in the identical location, it should not notice, but out of an abundance of caution, you could temporarily change your default browser at the system level while removing the old folder.

Step 4: After closing out of Firefox, rename the current program folder. While the odds of needing anything from it are low, it's a standard precaution. So

C:\Program Files\Mozilla Firefox\ => C:\Program Files\OldFirefox\

Step 5: Run the installer you downloaded in Step 2. It should discover your existing profile and launch with all your regular data.

Does the new installation behave any better?

So, I uninstalled and reinstalled (clean) and the problem appears resolved. My main Firefox process is holding at between 700-900MB, rather than gobbling up to 40 GB+ and crashing.

Thanks to all of you for you input and suggestions. Helpful. I appreciate it. -Mike