Safari 15 CPU spike and slowness

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Level 1

13 points

Safari 15 CPU spike and slowness

Since updating to Safari 15 (on Big Sur), been experiencing high CPU usage, slowness, and a hot laptop (macbook pro 16") whenever Safari is open. Goes away when I close Safari. I'm seeing 99%+ CPU usage from Safari and high usage from safari content blocker ext. I chose to uninstall AdGuard, and that seemed to calm down the content blocker extension.

After a restart it seemed good for a while, until I opened a New Safari Window, CPU spiked, etc again. So I thought I had pinned this down to multiple windows open being the cause. However, another restart and the CPU usage and hotness continue.

Anyone else basically unable to use Safari 15 without high cpu usage and general slowness? I have been using Chrome to get buy and no issues there.

MacBook Pro 16″, macOS 11.6

Posted on Sep 30, 2021 12:56 PM

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Answer 1

Best reply

slingstyle Author

Level 1

13 points

Oct 4, 2021 12:15 PM in response to slingstyle

I've tried many things. However, it seems at this time that switching the Tab Layout to "Compact" in Safari 15 that the high CPU, slowness and overheating go away. Even when I open multiple windows. As soon as I switch back to "Separate" layout, the CPU goes back up to 99%+ and problems return. I prefer the Separate layout, but can deal with Compact if it means things work like normal again.

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Answer 2

Eric--F

Community Specialist

Oct 1, 2021 11:15 AM in response to slingstyle

Hi slingstyle,

Thank you for using the Apple Support Communities.

It sounds like the Safari app on your Mac isn't working as expected and we have found some Apple Support articles below that can help.

If Safari doesn't open a webpage or isn’t working as expected

Keep your Mac notebook within acceptable operating temperatures

If an app on your Mac stops responding, closes unexpectedly, or won’t open

For more help with Safari visit the Safari Support page.

Best regards.

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Answer 3

Oct 4, 2021 9:43 PM in response to slingstyle

This worked for me as well. CPU reliably jumps to 99% when "Separate" tab layout is enabled, down when disabled, and so on... Side note, I constantly see quite a few bugs with the Separate layout. Redraw errors (i.e. disappearing tabs), unpredictable dragon behavior, etc. As a developer myself, I'd say this feature did not receive adequate QA. Cheers

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Answer 4

Yuna90

Level 1

11 points

Oct 20, 2021 2:02 AM in response to slingstyle

I run only into the issues on BigSur 11.6 only when I have two winnows of Safari opened. Maybe that helps a bit to reduce the pain :( Now I started to use Chrome and Safari in parallel just to get another browser window :(

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Answer 5

Nov 15, 2021 1:34 PM in response to slingstyle

Switching to "compact" tabs did it for me, thanks! I'm not a fan of the new layout and will definitely be checking to see if this bug's fixed when there's a Safari update, but this makes it actually usable.

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Answer 6

Fransjr

Level 1

4 points

Oct 15, 2021 2:57 AM in response to slingstyle

The moment I switched the layout to compact, the high CPU vanished. This is the solution I was looking for (for now) Hopefully Apple will address this issue in an upcoming update. Thanks!

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Safari 15 CPU spike and slowness

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