I'm on 10.15.2 Catalina, and my fans have currently been running steady for hours. I opened Activity Monitor, am viewing the CPU tab, and sorting by % CPU. Safari is at 102.6 as I type this.

Activity Monitor used to break down Safari by the open tabs, so you could easily identify the worst offender. Unfortunately in Catalina I just see "Safari".

How else can I determine which tab(s) is/are the main culprit?

  • apple.stackexchange.com/a/127111/341892 - will this help ? – Udhy Mar 10 '20 at 16:17
  • Unfortunately no @Udhy, those all seem to be for older OS/Safari versions – djibouti33 Mar 10 '20 at 17:52
  • Are you in 'all processes' or 'all processes, hierarchically' view? Hierarchically will group the windows inside the 'folder' Safari, all processes will list each as its URL, with no real 'link' to Safari itself. – Tetsujin Mar 10 '20 at 19:52
  • wonderful @Tetsujin! Had no idea that was an option. Thanks! If you respond as an answer I'd be happy to select it as the winner. – djibouti33 Mar 12 '20 at 5:45

From comments…

In Activity Monitor, if you set the View to "All Processes, Hierarchically" then all sub-processes of Safari [or anything] will be contained within the main process, aiding the task of discovery.

  • I followed your instructions and they worked perfectly. However, right now my fans are all on, and I see that Safari is using 100.4% CPU. If I view Hierarchically, I can open up Safari and see sub-processes. The first tab listed is 3.3%, then 0.5, 0.1, and then everything else is 0.0. Seems like this method still doesn't accurately report the misbehaving tabs. – djibouti33 Mar 18 '20 at 20:15
  • The figure for Safari itself is not a total of the other figures, it's Safari's actual usage. To get the total you literally have to add all the sub-processes to the main figure. Having said that, I've never known Safari itself to be using a whole core. Have you tried rebooting, &/or closing all windows & re-checking? – Tetsujin Mar 19 '20 at 8:16
  • Late thought - it might be a runaway extension. idk how they are reported in Activity Monitor, but it might be worth disabling any extensions & re-testing. – Tetsujin Mar 19 '20 at 9:31

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