The same problem was occurring on the High Sierra. I was hoping it will be fixed on Catalina but unfortunately, I didn't.

I use Catalina 10.15.1 on my MacBook Pro and work with an external monitor that is connected with HDMI.

The issue is that, according to Activity Monitor, the kernel_task process consumes more than 600% of CPU even when no tasks are running. The computer becomes totally unusable. I cannot switch between screens and everything freezes.

As a solution, I disconnect the external monitor.

Why didn't Apple fix this issue in the latest Catalina update?

=> Is there an alternative solution for this?

I have followed for the rMBP kernel_task spikes when connecting more than one external monitor [duplicate]

I managed to disable system file protection using csrutil disable, but on Catalina now I am having the following error:

mv: rename X86PlatformShim.kext to X86PlatformShim.kext.disabled: Read-only file system
  • 1
    An important thing to remember is that computers (this isn’t limited to Macs) that use integrated video (i.e. Intel Iris) you’re using the CPU and system memory to process video. Another monitor = more processing load. This alone impacts the performance of your Mac.
    – Allan
    Apr 11, 2020 at 13:01

2 Answers 2


From your observations it sounds like you have a temperature problem with your MacBook Pro. The system makes the CPU sleep when it detects a temperature problem - this what makes it appear as if kernel_task consumes all the CPU time (it actually doesn't). Usually this is due to either: (a) fan problems, (b) blocked vents or (c) lack of cooling paste.

I would check these to make sure that fans are working properly, the machine is not full of dust, the vents are free and cooling paste has been applied properly to the CPU.

  • I am using cooling pad and Macs Fan Control app the fan control for but I guess it does not help much. I will check your recommendations and will update @jksoegaard
    – alper
    Nov 20, 2019 at 8:54

Enter sudo mount -a before sudo mv X86PlatformShim.kext X86PlatformShim.kext.disabled

  • I did not understand what is this solution for ?
    – alper
    Jan 1, 2021 at 12:48
  • Please add details on why you think this is an acceptable solution. We discourage one line answers on AD as one of the objects is to inform the troubleshooting process and not just provide a copy/paste solution with no exposition. Jan 1, 2021 at 15:34

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .