Safari using all my CPU M1 Macbook Air

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Possum66 Author

Level 1

14 points

Safari using all my CPU M1 Macbook Air

Safari 27.2 is using all my CPU on my M1 Macbook Air.

Launch Safari 27.2 on macOS Tahoe 26.7.2

Feel your lap get warm within a few seconds, then hot.

Launch Activity Monitor and witness Safari using all the CPU

Starting last week this began happening on macOS 26.7.1 (and whatever version of Safari came with Tahoe 26.7.1).

I updated to macOS 26.7.2, and even after a fresh update/restart this is happening.

Safari is basically unusable right now, and I must force-quit to kill it. Chrome does not have this behavior (Version 156.0.8078.48).

Posted on Oct 27, 2026 4:12 PM

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Answer 1

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Possum66 Author

Level 1

14 points

Oct 28, 2026 6:34 AM in response to Possum66

I think I found the problem and want to post my solution.

I found a record of saving a URL with the Southhampton.uk address last week, right around the time this issue with Safari started.

I had read an article that posted a link to an online textbook on Quantum Mechanics, by a professor at this University. I saved the link to my Reading List in Safari, in addition I created a text file with the URL and saved it to my Dropbox. As I was saving a new URL to my Dropbox this morning I saw my last save, which was this address. Apparently I had a relationship with this URL.

I started up Safari and deleted the link from my Reading List, and all seems normal again. Something about that link was eating my CPU cycles.

Here is a similar Activity Monitor screenshot as before running Safari with all my extensions active and Dropbox re-enabled as a Login Item.

Thanks for all the suggestions, this one had me concerned about something more nefarious.

peachpossum

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Answer 2

Oct 27, 2026 6:41 PM in response to Possum66

And just for reference, when you see 100% in Activity Monitor that is just for a single core. Your MacBook Air has 8 CPU cores, so a reading such as that is not even close to using your entire CPU.

With that said there are 2 other things to check that will produce heat and slow performance:

Remove/disable all Extensions at Safari > Settings > Extensions.
It certainly is possible to have a runaway process from a webpage and that will show in Activity Monitor as that web page, such as www.cnn.com and you can quit that process where it will then return to normal. No need to Force Quit Safari.

Typically Chrome uses much more CPU than Safari due to its data harvesting, but there are other Chromium based browsers, such as Brave, that will use less CPU than Chrome.

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Answer 3

TheLittles

Level 10

210,963 points

Oct 27, 2026 6:13 PM in response to Possum66

"Safari using all my CPU M1 Macbook Air: [...]Safari 27.2 is using all my CPU on my M1 Macbook Air.[...]I updated to macOS 26.7.2, and even after a fresh update/restart this is happening."

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Exit Safari:

Get to Finder, and then Force Quit Safari...

Go Here: [command + tab] Use it to Access your Mac when Something is Not Responding - Apple Support

Then, Force Quit Safari:

Click: the Apple emblem in the Finder bar
Select: Force Quit...
Select: any item ending in “(Nor Responding...)”
Click: Force Quit button

Start in Safe Mode:

In Safe Mode, Login Items do not open at login. Go Here: Start Up your Mac in Safe Mode - Apple Support

Then...

Remove Login Items:

Go to: System Settings > General > User Name > Login Items & Extensions
Select: an Item
Click: the “—“ button
Approve: of the removal in the popup window.

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Answer 4

Possum66 Author

Level 1

14 points

Oct 28, 2026 5:59 AM in response to TheLittles

I tried all suggestions above plus a few extras, repeated here for clarity;

1.) Disable all Safari extensions in Safari Settings

2.) Clear my Safari Cache

3.) Restarted in Safe Mode

4.) disabled all Login Items (it was only Dropbox.app)

5.) While in Safe Mode, launch Safari

6.) Safari is still using nearly 100% of all my 8 cores.

When I quit Safari, nothing happens except the the Quit Menu item becomes greyed out. I still have to force quit Safari to get the window to close.

I've attached a picture of my Activity Monitor and the CPU Useage graph.

I do notice a suspicious web address in the list of active processes. This is not a site I knowingly have any history or relationship with. It is boxed in red in the attached screenshot. Again, this screenshot was taken while in Safe Mode.

Appreciate the suggestions so far. Any further suggestions welcome.

peachpossum

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