Windows 11 after July 25 update - pegging performance cores, keeping fans running

R

RandomParallelsUser

Junior Member
Hi -

Macbook Pro M3, latest Sequoia 15.5, latest Parallels build, just loaded Windows 23H2 July update. Everything seemed to work fine - but I noticed that the machine was still pegged (fan running, temp high). I rebooted the mac, booted back into Parallels/Win11, and it ended up with the same issue. If I run Task Manager, it shows the CPU at 60%, with the highest (and only) task showing as "Task Manager". I've let it sit like this for 30+ minutes, hoping it's some type of setup or cleanup task, but that doesn't appear to be the case.

Something with today's Microsoft Windows update disagrees with Parallels - and it will make it unusable on battery. It may work while plugged in, something clearly isn't working correctly.
 
Exactly the same here - after the update (23H2), running on M3 Max/Sequoia 15.5, my Windows 11 VM in Activity Monitor running at 700% CPU.

Restarted, reinstalled Parallels Tools, Restarted, let it sit for 24 hours, still the same. Not good.
 
I have the same, Macbook Pro M3 Max. I registered support ticket for it and pointed support to this topic. I hope there will be a fix soon
 
Same here on an M4 Max, Sequoia 15.5 (24F74), Parallels 20.4.0 (55980), Windows 11 23H2 build 22631.5624.

Windows task manager shows a continuous 50% CPU utilization with no actual tasks running, and my Mac's performance cores are all being hammered.
 
Uninstalling the July fix KB5062552 resolved it for me, I got instructions from Parallels support for this, really great. As this will help others too I repeat them here:

Following your report regarding high CPU usage after updating Parallels Desktop and Windows, we would like to inform you that this issue has been identified to be caused by a recent Windows cumulative update - KB5062552, released on 8th July 2025.

As a temporary solution, we recommend uninstalling this update from your Windows virtual machine using the steps below:

1. Start your Windows virtual machine.
2. Go to Start Menu > Settings > Windows Update.
3. Click on Update History.
4. Scroll down and click Uninstall updates under the "Related settings" section.
5. Locate KB5062552 in the list.
6. Select it and click Uninstall.
7. Follow the on-screen instructions and restart the virtual machine once done.

Please note: This is a temporary workaround until Microsoft releases a fix. We will continue monitoring the situation and update you once a permanent resolution is available.
 
+1. Windows 11, Mac Mini M2 (Sequoia 15.5); Windows pinned at "CPU x 100%". It's the first time I've known the fans in my Mac Mini to actually be audible.
 
GeoPPP20 said:
FYI, installing 24H2 Fixed this. Unfortunately the 24H2 update would not appear for me in Windows Update, so I followed the flagged "Best Answer" here https://forum.parallels.com/threads/how-to-update-windows-11-to-version-24h2.366241/ to force the download and installation of the latest Windows update.

The CPU is back to almost zero when idle. Same with Win 11 instance in Activity Monitor. All good.
Click to expand...

Interesting! Is 24H2 supported by Parallels? Does everything work reasonably well? I wasn't concerned that it was still on 23H2 and thought the 24H2 would be enabled (by MS & Parallels) once it was supported.
 
I had same issue - MacBook Air M3 chewing through battery and getting really warm. Uninstalled KB5056580 and KB5062552 and it's calmed right down! Phew! Thanks to everyone who posted their resolutions above
 
Yes - this seemed to work. Fan is stopped, temps are down, Windows is at 24H2. Here's a link with instructions. That's the method that worked for me - downloaded the ISO file, installed 24H2. After a reboot or two and letting it set, all seems well.
 
I have the same problem with Windows 23H2, but since the machine is managed, I am unable to revert the patch - stuck with 50% loss of CPU, since MS released the patch last week Tuesday.

Parallels - I'm curious, is this issue affecting many users? Can you check / share any metrics or data that can help understand the scale of this problem?
 
Just had the latest Parallels update. and processor back pegged at approx 50%. Uninstalled all the Windows updates I can now, and still have the issue :(
 
Uninstalling both KB5062552 and KB5062663 is the temporary fix for me.
Has the parallels team addressed the problem in 20.4.1 (55996), or can anyone confirm that Microsoft has fixed it in a later cumulative update? Thanks.
 
I am still stuck with 50% of the CPU pegged - keeping my hands nice and warm.

Waiting for a Windows 23H2 Enterprise patch or Parallels patch to come through. Does anyone know when this might happen?
 
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