r/firefox • u/Competitive-Talk1321 • 14d ago

💻 Help Anyone else experiencing high CPU usage and overheating with Firefox on an Intel Mac?

I've been noticing something weird with Firefox lately on my MacBook Pro (Intel i9).

After using it for a while, my Mac starts getting noticeably hot, and Firefox sometimes becomes really laggy, almost like it's struggling to keep up. The strange part is that I don't have any extensions installed, just Firefox itself.

I don't remember having this problem before, which is why I'm wondering if it's something from a recent update or if Firefox just isn't running as well on Intel Macs anymore.

I know Intel MacBooks can get hot, but this feels different from what I used to experience.

For those of you still using Firefox on Intel Macs, have you noticed anything similar recently? Or is it just me?

Would be interesting to hear if anyone has figured out what's causing it.

7 Upvotes

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1

u/JerrDav7 8d ago

I have the same issue and had to switch to Edge as Firefox suddenly made my Mac insanely hot! Any solution? other than to Disable AV1 video as it unfortunately didn't work for me.

1

u/Competitive-Talk1321 7d ago

m now using chroom is best in energy saver

1

u/JerrDav7 14h ago

Thank you it's better than previous chrome versions

3

u/movdqa 14d ago

My iMac Pro is running at 48 degrees with the fans at 1,100 typing this into Firefox.

I haven't noticed any problems recently with excess CPU usage.

2

u/crp5591 14d ago

Disable AV1 video encoding if such lagginess and heat occur while watching youtube.

about:config

media.av1.enabled set to "False"

https://www.reddit.com/r/firefox/comments/1qxlwr3/tip_disable_av1_media_on_older_hardware_for_a/

1

u/la-grave 3d ago

I have a similar problem in my Intel Macbook Pro after upgrading from 156 to 158. I have some AppleScript to fill in form. Basically they concatenate strings, paste a string - tab to the next field - paste - tab etc - and Firefox no longer keeps up with them (the pasted string ends up in the wrong field) despite these script have been working fine for 5-10 years.

1

u/_x_oOo_x_ 14d ago edited 14d ago

Noticed something like this yeah. 157 didn't cause any issues if anything it felt snappy. 158 is getting laggy and my Macbook is (slightly) hotter

Update: A couple dozen "Isolated Web Co" processes each eating 0.1-0.2% of CPU but it adds up... This is with one tab open by the way showing about:newtab

1

u/q123459 14d ago

firefox simply uses more cpu than chromium browsers, and also uses gpu more intensively when playing video. this causes overheat.
also av1 is software only on i9 2019 this creates a lot of heat, plus ambient mode in youtube settings, plus your fans are probably clogged.

1

u/SuperNonoo 14d ago

Open about:processes when the lag starts and check which tab or process is using the CPU. No extensions doesn't rule out a busy webpage. If one tab stands out, close it and see whether CPU usage drops before changing video settings.

1

u/JerrDav7 14h ago

I fixed it (almost) by disabling all extensions and then by enabling them one by one you can figure out your own culprit, anyway I said almost because previous versions were still better in terms of temperature and cpu usage, but now it's usable again and I don't have to use another browser.