The configuration file option monitor.SleepWhenIdle determines whether the VMkernel deschedules an idle virtual machine. By default, this option is enabled, a setting that ensures much better performance when running multiple virtual machines.

When you are running only a single virtual machine (such as for benchmarking VMware ESX Server), add the monitor.SleepWhenIdle option to the virtual machine's configuration file if you want to achieve the best possible performance in the virtual machine (at the expense of responsiveness in the service console).

Create an option called monitor.SleepWhenIdle and set the value of this option to 0, as described in Modifying the Configuration File Directly (Advanced Users Only).