Safari keeps running with high CPU usage

meme1255

macrumors 6502a
Original poster
Jul 15, 2012
714
544
Czechia
Hi, ever since I've upgraded to 10.14.5 Safari on my MBP keeps lagging every once a while – it eats 100 % of one core and iStat Menus shows it as "zombie" (red) for that time. I've tried disabling all plug-ins, it didn't help. I cannot find anything relevant in logs either. Do you have some ideas? Thanks.
 

Honza1

macrumors 6502a
Nov 30, 2013
514
178
US
1. Disable all extensions. May be one of them is not compatible with 10.14.5 version of Safari. May be there are updated versions?
2. Create a new user and try to run Safari there, that will tell you if this is system wide or user specific.
3a. If it is system wide, I would reinstall 10.14.5 using combo installer. Ideally, I would reinstall just Safari, but I think this is the only way to reinstall Safari.
3b. If it is user specific, something is wrong with Safari specific setup in that user account. What, not sure. Clean cache seems good idea, remove extensions,...

Before you do ANYTHING., backup your computer.
 

Fuchal

macrumors 68020
Sep 30, 2003
2,449
707
I've had the same issue ever since Mojave, and even a complete re-install didn't help. I gave up trying to figure it out.
 

960design

macrumors 68030
Apr 17, 2012
2,966
924
Destin, FL
Poor JavaScript coding is occasionally the culprit.
Or dare I say, excellent JS coding that uses your computer to hash crypto in the background while you are viewing a page.

I recommend the next time you see the 100% or feel the slowdown to temporarily turn off JS and reload the page. See if that changes anything.
 

HDFan

macrumors 68020
Jun 30, 2007
2,121
529
Are you using an adblocker? I had an issue where Safari had a runaway process that took 32 GB of memory. Installing an adblocker got rid of the problem.
 

Fuchal

macrumors 68020
Sep 30, 2003
2,449
707
Poor JavaScript coding is occasionally the culprit.
Or dare I say, excellent JS coding that uses your computer to hash crypto in the background while you are viewing a page.

I recommend the next time you see the 100% or feel the slowdown to temporarily turn off JS and reload the page. See if that changes anything.
I have the problem even when there are no Safari tabs open at all - there's a rogue Safari Web Content process that doesn't seem to ever shut down. Quitting Safari seems to be the only solution once this happens.

Are you using an adblocker? I had an issue where Safari had a runaway process that took 32 GB of memory. Installing an adblocker got rid of the problem.
Have had the same problem while using Wipr or Adguard.
 

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