Fusion Windows 10 VM keeps freezing issue on macOS Big Sur 11.6.8

[AlanDM111S]

I run a Windows 10 VM using Fusion 12.2.4 and I have used this VM for a number of years. Since upgrading to Big Sur, I have an issue with the Windows VM where the VM will 'freeze' and input (keyboard or mouse) is not recognised for a few seconds. Once the VM 'unfreezes', most Windows apps are in the background and Windows Explorer is now in the foreground. In other words, I have to click the Windows app I was using on the Taskbar to carry on with my work.

The situation is worse when I'm on a Zoom call and sharing my screen on the Mac or I have the camera switched on as this happens every 15-20 seconds or so as opposed to every few minutes normally

Is this a known issue, or is my Mac just not powerful enough any more ?

[ColoradoMarmot · Accepted solution]

Big sur definitely puts more load on the host.  What's the host and guest configuration?  You need to have at least 2 cores for the guest, but no more than N-1 cores (where N is the number of physical cores in the host).  Ideally you'd leave at least 2 for the host as well (which means a 4-core machine).  Ditto on the memory - at least 2GB for the guest (preferably 4), and at least 2 for the host, and 4 for best performance (which means at least a 4GB host, 8GB ideally).

[AlanDM111S]

Thanks for your reply:-

The Host is:-

Model Name: MacBook Pro
  Model Identifier: MacBookPro11,2
  Processor Name: Quad-Core Intel Core i7
  Processor Speed: 2.2 GHz
  Number of Processors: 1
  Total Number of Cores: 4
  L2 Cache (per Core): 256 KB
  L3 Cache: 6 MB
  Hyper-Threading Technology: Enabled
  Memory: 16 GB

The Guest is set to 4 cores and 4GB so maybe if I drop it down to 2 cores that will make the difference.

[AlanDM111S]

@ColoradoMarmot Although I've marked your answer as an accepted solution, I have to say that my VM still freezes but only rarely now (1-2 times per day) compared to often (every 30 seconds) before.

Many thanks for your help

[ColoradoMarmot]

You bet.  What we're finding is that as Apple's OS's get more sophisticated, they consume more resources.  A 4-core machine is fine for regular use, but it's becoming marginal for running VM's.

The good news is that the M1's absolutely rock for multiple VM's.  We haven't figured out the guidance on cores yet, basically because it's difficult to get the machine to slow down without running a crazy number of VM's with high configurations.