Your host CPU usage is not "very high".12% or higher is quite normal if the guest is busy, for example installing OS updates. Try running the task manager in the guest and see what keeps it busy. When the guest CPU usage drops at ~0%, the VMX process in the host will also drop to ~0%.
If the problem persists, as a precaution make sure don't overprovision your VM - try reducing the number of CPU cores and limit RAM to 4GB.