Firefox may use more system resources if it's left open for long periods of time. A workaround for this is to periodically restart Firefox. You can configure Firefox to save your tabs and windows so that when you start it again, you can start where you left off.

I already do that.

Try entering about:memory in the address bar and press the button labelled Minimize memory usage. You may have to press several times.

https://support.mozilla.org/en-US/kb/firefox-uses-too-much-memory-or-cpu-resources

Visit about:processes and about:memory in the address bar to find where exactly the memory usage is occurring.

Capture a performance profile during high memory (but not too high) and share the link here.

Does it still happen with hardware acceleration disabled?

This is another workaround that does not work. The underlying FF memory management defect needs to be fixed and this problem was identified over 6 years ago. Memory management should be completely user transparent without requiring any manual intervention. Often, the only warning that a user gets when FF has hogged excessive memory is that the user interface begins lagging and freezing without warning. This defect causes FF to be practically unusable on smaller and older systems, many of which are still needed, on which Chrome browser still works fine. The developers on the FF project need to fix the memory management system. This is the only viable solution. The 6 year old bug report is still outstanding and has never been solved. Get with it!!! In the meantime, FF system requirements should be updated to admit that FF often performs poorly on systems with 16 GB of system RAM or less, and with older CPUs like Pentium or Celeron.

zeroknight: I will wait until my total physical memory usage exceeds 16 GB (out of 32 GB minus the Intel integrated graphics allocation) and then I will record the info that you have requested. Total memory used is currently at 12.4 GB. I don't recall baseline just after FF restart with the current tabs that I have open, but I think it is around 4 to 6 GB. I will also include the memory usage immediately before and after FF restart with no other apps altered. TY for your attention to this.

I've only had it open an hour, haven't watched any videos or streams of any kind, and it's using 10.5 GB of the 16 Gigs of RAM on my Macbook Pro. This after "updating" three times within an hour, refreshing it each time, which is nuts, and it's still sucking up most of my RAM... It's a mess.

If you check the about:processes page (Shift+Esc), can you associate high memory usage with any particular process or website?

Mine shows 4GB of memory for GPU, 1GB for Firefox, and smaller amounts for other processes. I do have 46 windows open, so I might be an extreme case...

So far, I have not associated the excessive memory usage with any specific processes or tabs. I will look into this further. I recently had a FF process crash and had to restart FF, but not my PC OS (Win10). I had FF open for several days continuously without restarting it. I have 32GB total physical memory. Physical memory use was 23.1GB at the time of the process crash. When the process tree was stopped, 6.4GB remained in use by the system and other application processes. After I restarted FF, total physical memory usage increased to 8.4GB with all tabs restored as they were at the time of the crash, so 14.7GB of memory was freed just by restarting FF. This seems like an excessive amount. I have a lot of tabs open, IDK how many. I have 10 FF windows open. According to Process Explorer, FF has 35 processes active in the process table and 10.7GB of physical memory in use for the entire system as I write this. It is running fine with good responsiveness.

If you check the about:processes page (Shift+Esc), can you associate high memory usage with any particular process or website? Mine shows 4GB of memory for GPU, 1GB for Firefox, and smaller amounts for other processes. I do have 46 windows open, so I might be an extreme case...

I show Firefox using just 1GB of Memory, yet fluctuating CPU usage of 80% - 130%, and I'm not streaming or playing any media whatsoever. My Activity Monitor shows FF using 2.5 GB memory, & around 100% of CPU usage. The total FF memory is using nearly all 16GB of my Macbook's RAM! Why? I've got a lot of windows open (about as many as you), but as I said, no media playing, no streaming, etc...

jscher2000 - Support Volunteer said

If you check the about:processes page (Shift+Esc), can you associate high memory usage with any particular process or website? Mine shows 4GB of memory for GPU, 1GB for Firefox, and smaller amounts for other processes. I do have 46 windows open, so I might be an extreme case...

I show Firefox using just 1GB of Memory, yet fluctuating CPU usage of 80% - 130%, and I'm not streaming or playing any media whatsoever. My Activity Monitor shows FF using 2.5 GB memory, & around 100% of CPU usage. The total FF memory is using nearly all 16GB of my Macbook's RAM! Why? I've got a lot of windows open (about as many as you), but as I said, no media playing, no streaming, etc...

Hopefully you can use the built-in Task Manager (about:processes) to backtrack heavy memory or CPU use to specific tabs.