VMware gives you the option to set the process scheduling priority for the virtual machine. There are three possible process scheduling priorities: idle, normal and high. The typical process on the host runs at normal priority. If you set the virtual machine's priority to normal, the virtual machines's process will contend with all the processes on the host. If you set it to idle, the virtual machine will have lower priority than other processes on the host. If you set it to high, the virtual machine will get priority over other processes on the host.
VMware gives you the option to automatically change the process scheduling priority when the virtual machine obtains or loses input focus. The default is to run with normal priority in all cases.