Fix the MacBook Big Sur slowness

I used to be able to run 3 VMs on Vmware Fusion at the same time on Catalina. After I upgraded my MacBook Pro to Big Sur, even 1 vm could cause slowness. If I run the vm along with Teams or Zoom meeting, it simply stopped responding. I couldn’t even move the mouse sometimes. 

 

My MacBook is Pro 2019, 32G memory, 2 video cards. CPU: 2.3GHz, 8-Core Intel Core i9. This configuration is not that bad.

 

I googled and found many users have the same problem. And there were many solutions. However, I’ve tried all of them, including but not limited:

1.    Disable "Enable hypervisor applications in this virtual machine"

2.    On the guest windows, on settings > Windows Security > device security > turn off “Memory integrity”

3.    Modify the .vmx file (https://communities.vmware.com/t5/VMware-Fusion-Discussions/VMware-Fusion-12-1-0-Big-Sur-Host-Windows-10-Guest-Running-Slow/m-p/2814913/highlight/false#M170980)

4.    Set windows.vbs.enabled = "FALSE"

5.    Use Parallels but it seems to have the same problem.

 

After many attempts, I am thinking of moving back to Catalina, however, it means a lot of work because I didn’t have the backup in Time-Machine. 

 

It would be better if the issue could be solved in Big Sur so I don’t have to rollback. 

 

I started my investigation. So far in my MacBook Pro, there were 4 applications that could cause the slowness: VMware Fusion, (Parallels), Teams, Zoom. I noticed whenever the slowness happened, there was a process call “kernel-task” that has more than 1000%CPU usage and the fan was running like crazy. 

I googled what “kernel-task” is really doing, on Apple support site (https://support.apple.com/en-ca/HT207359), it mentioned: 

 

Activity Monitor might show that a system process named kernel_task is using a large percentage of your CPU, and during this time you might notice more fan activity. 

One of the functions of kernel_task is to help manage CPU temperature by making the CPU less available to processes that are using it intensely. In other words, kernel_task responds to conditions that cause your CPU to become too hot, even if your Mac doesn't feel hot to you. It does not itself cause those conditions. When the CPU temperature decreases, kernel_task automatically reduces its activity.

 

So, I think, if I cool down the laptop, maybe this process won’t use that much CPU resources. 

 

I bought a laptop cooling pad, it helped, now I can run 1 vm without any slowness. However, I still couldn’t run more than 1 vm at the same time. 

 

I need a stronger cooler, so I took a First Aid Ice pack from the refrigerator and put it under the laptop. Now, I can run 3 vms at the same time again.

 

I think maybe Apple changed the way of how the process “kernel_task” be triggered on Big Sur to better protect the CPU. but it causes the whole system to be slow.