- My computer fans speed up and Mac starts to heat up.
- My virtual machine's process (prl_vm_app or Parallels VM) in the Activity Monitor consumes 100% of Mac CPU or above.
High CPU usage by virtual machine's operating system.
The maximum utilization of every CPU unit assigned to a virtual machine in Activity Monitor counts as 100%. For example, if your virtual machine has 4 CPU units assigned, then a total amount of CPU utilization by a VM will be 400%. To check how many CPU units are assigned to VM open configuration window > Hardware > CPU & Memory.
NOTE: We highly recommend using the recommended number of CPUs. Assigning a more recommended number may cause performance degradation of both Mac and a virtual machine.
Users who use their virtual machines rarely may encounter slowness and other performance issues after starting a virtual machine if it wasn't used a long time. From our side, we recommend you to give Windows some time to finish doing necessary internal jobs and other required maintenance tasks. If Windows still working slowly, check Task Manager as described below to find out the reason for CPU consumption.
The virtual machine's CPU consumption directly depends on guest operating system usage. If you notice that your virtual machine consumes a high amount of CPU resources, check CPU consumption in the guest operating system in Task Manager (right-click on Windows taskbar > Task Manager):
Once you determined what process of Windows program consumes a sufficient amount of CPU, you may refer to the software manufacturer's knowledge base to find more information. For some types of software, like video or photo editing, CAD, or videogames, high CPU usage is a common operating condition.
If you find that this process belongs to Windows OS, please note that the following system actions cause high CPU usage:
- Downloading and installing Windows updates
- File indexing
- Driver incompatibility issues
- Redundant startup applications
To find out the reason for high CPU usage in your case, note the process name and refer to Microsoft Support or third-party resources for more information.