Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

Firefox uses too much memory (RAM) - How to fix This article describes how to make Firefox use less memory to make it run faster and prevent crashes.

https://support.mozilla.org/en-US/kb/firefox-slow-how-make-it-faster

https://support.mozilla.org/en-US/kb/firefox-uses-too-many-cpu-resources-how-fix

https://support.mozilla.org/en-US/kb/firefox-hangs-or-not-responding

As I said, I already tried all those supposed fixes, multiple times. FF is just a huge hog.

What are you using as anti-virus?

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

You are having a very hard time understanding.

I said twice now that I already tried all those supposed fixes.

I use Avast for Mac. Independent of FF. Doesn't use but a blip of CPU, whereas FF uses 70 -- 110% (don't know how the latter is possible, but that's what shows). Fan is off when FF is closed, always screaming when it's open, even in the background.

Compare to Chrome and Safari, using only 0.2 - 0.4 CPU, with similar number of addons/plugins.

seeclear said

despite doing all the fixes suggested, repeatedly.

But, you did not state what you had already tried.

I've called the big guys to help you. Good luck.

Everything in that list you provided PLUS more in the Mozilla knowledge base. Thank you.

I got impatient because your answers seem to be more of the same denial that's been going on in Mozilla about this issue that has been plaguing users for years.

I really like FF, but the memory usage has made it too problematic. I am back to Safari as my default browser.

I too am experiencing the same thing on my iMac, w/12 Gigs of RAM... No matter if I have only a couple or lots of windows open, as time goes on, the RAM hogging steadily increasing, until it becomes unresponsive, or very, very slow, especially when trying to write something, constant spinning balls... Stop Script windows popping up, this with nearly nothing open but a couple tabs in one window, and no Flash being used!

It'll go from around a Gig or memory at the beginning, up to 3 Gigs, or several times up to 4 or more, with per cent CPU usage jumping up to 200%, even as high as 790, or even 1,200, and once it even read 2,000%! Which I know is crazy.... but that's what it reads. Then when I go to shut it down, to reboot it, and start the climb all over again, it will take sometimes five minutes to finally shut down, with the usage levels spiking way, way up, even as it's shutting down! I mean, what the heck is that all about?

I like using FF, but this is getting really old, and as seeclear's posts reveal, the usual fixes don't seem to do anything, and it's been doing this for too long...

When do the big guys come in to help us with this?

When they can. Many other users also need help.

Who wants to bet they ever do?

In the Activity, what specific metric are these percentages?

Do you happen to have the version number of Firefox when this started happening? This can help narrow down what edits to look through :-)

Also the Telementary data sent on the browsers can help improve the performance. There are also automated tests done to check performance of different platforms.

If you are interested in providing a website example this could help create a bug. With the websites, there are have these tools to test the performance of the profile as well: This will test the javascript engine on desktop: *https://developer.mozilla.org/en-US/d.../Reporting_a_Performance_Problem

We look forward to your reply

Do you anybody for whom FF isn't gulping huge amounts of CPU?

I've consistently found the worst performance is on Facebook, videos are slow even jerky, lots more RAM use, slowing, etc... Today, I saw my CPU usage jump up to almost 300%, with it using about 3 GIGS of RAM. I can only use it a few hours before having to close it and open it again, and closing always takes forever...

It would be really great if there were a way of determining how much CPU was being used by each tab in each tab group in each window. That way I could figure out which tabs to close when I don't immediately need them anymore, instead of leaving them around for the next time I want to reload and look at them.

"In the Activity, what specific metric are these percentages?

Do you happen to have the version number of Firefox when this started happening? This can help narrow down what edits to look through :-)

Also the Telementary data sent on the browsers can help improve the performance. There are also automated tests done to check performance of different platforms.

If you are interested in providing a website example this could help create a bug. With the websites, there are have these tools to test the performance of the profile as well: This will test the javascript engine on desktop: *https://developer.mozilla.org/en-US/d.../Reporting_a_Performance_Problem"

--- This is an exercise in futility, and I am convinced that, if not you, then the lead developers know it. It's been going on since way back in early versions of FF, and it's not any website, but the entire browser, regardless if there are 50 tabs open or one.

Right now, with one blank screen window open, FF is vacillating between using 13 to 27 %.

Here's a sample shot of the kind of issues we deal with,...

I feel for you, Seeclear! I've had the same problem for ages. And yes, I, too, have spent days, weeks and months doing every fix Mozilla suggests and half the stuff on the forums, to no avail. YES my FF is updated to the latest version. It's NOT my computer. It's NOT my modem. It's NOT my ISP. It's NOT my firewalls. It's NOT my anti-virus. It's NOT any of the utter beginner ignorance stuff that's in most of the FAQs and How To's. It's NOT my addons or plugins (which I get sick of disabling and uninstalling to test Firefox only to find repeatedly that they are not the problem). I do NOT want to re-set FF and lose everything (again, for the umteenth time) only to have to set it all up again. Spend too much time troubleshooting and fixing as it is! I agree that Chrome and Safari go like rockets in comparison, but I don't like them. I LOVE Firefox - it's bookmarks handling, toolbars, everything. EXCEPT this CPU-eating problem. It will hog between 30% to 110% and I, too, spend WAY too much time watching rainbow balls spinning, and force quitting unresponsive programs.... while I'm trying to do serious, time-sensitive work. It spins so long, I forget what I was just about to do.... and the frustration gives me migraines! One good thing about it: I am learning to master frustration and stay calm and present with myself, detach, etc.

Well, either the big boys never got here, or came and couldn't do anything about this huge issue. Why it runs up in RAM & CPU usage, even if only two or three windows or tabs are open, is extremely frustrating & continues on. I've sent many, many bug reports, and nothing happens. I've used FF for many years, and this version of it 42, is the absolute worst, I never had this issue every day, several times a day, etc...