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"FirefoxCP Isolated Web Content" is slowly consuming all of my Mac's memory.

Making moves


I use the M1 MacBook air which has 8 GB of RAM. I use it with a 4k 144Hz monitor.

I was searching for a browser that can take advantage of my 144Hz monitor and run smoothly. Safari works only 72 Hz and chrome initially runs at 144Hz but gradually it becomes choppy after using it for 10 minutes. 

Firefox is the only browser that can sustain the 144Hz and everything runs very smoothly.

But here is the problem I am facing with Firefox. After 30 to 40 minutes of use, my whole laptop froze. When I checked the Activity Monitor it shows that "FirefoxCP Isolated Web Content"  is taking 10+ Gbs of memory.

Then I closed Firefox, everything goes back to normal. Then I opened Firefox again and closed all the tabs and put my MacBook to sleep. When I opened my MacBook, the laptop is already struggling to do anything. There was no tap opened and even in the laptop sleep mode"FirefoxCP Isolated Web Content" is gradually taking 12+ Gbs of memory.

I really want to use Firefox. I have tried all the browsers and Firefox is the only one that can run smoothly on my 4k 144Hz monitor.

So I am requesting you to help me solve this issue.

Thank you.


Making moves

I just had this same issue. After reading some of the replies here, I realized I had TWO Firefox tabs open with two different Amazon products I was keeping an eye on. I closed those two tabs and the CPU fan of the 2017 MBP almost instantly started to calm down and the machine resumed its usually snappy response times.

Making moves

Same issue here. Firefox Isolated Webcontent process took up 8 GB of RAM:

Firefox 109.0.1 (64-Bit)

Operating System: openSUSE Tumbleweed 20230222
KDE Plasma Version: 5.27.0
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8
Kernel Version: 6.1.12-1-default (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-7700K CPU @ 4.20GHz
Memory: 15.6 GiB of RAM
Monitor: Dell Inc. S2721DGF running at 144 Hz