The virtual machine process has CPU consumption above the one reported in Task Manager

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Symptoms

In Activity Monitor on your Mac you can see the Windows (prl_vm_app) process, responsible for running a virtual machine that consumes over 100% of your CPU.

 

At the same time, Task Manager in Windows Virtual Machine shows a reasonable amount of CPU to be used (~25%). Your Mac has more than one CPU installed.

Cause

The reason why numbers are different is that Mac and Windows calculate CPU consumption in 2 different ways:

Some CPU power on the Mac side is also used for virtualization purposes.

Based on the example on the screenshots above, 25% CPU in Windows virtual machine equals 25 × 6 = 150% on the Mac side, plus 17.5% for virtualization purposes. It means Parallels uses 167.5% CPU from 600% in total, so Mac has plenty of CPU left for other processes.

Resolution

In case your Mac has 2 or more CPUs, consumption of around 100% in Activity Monitor is acceptable and should not decrease your Mac performance. So no actions need to be performed.

If you feel the performance has been decreased, and you have troubles operating in Mac or Virtual Machine, please check KB 116263.

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