Using the Optimization Settings, you can optimize your virtual machine performance.
Using Adaptive Hypervisor
Select the Enable Adaptive Hypervisor option to automatically allocate the host computer CPU resources between the virtual machine and Mac OS X applications depending on what application you are working with at the moment. If your virtual machine window is in focus, the priority of this virtual machine processes will be set higher than the priority of the Mac's processes and as a result more CPU resources will be allocated to the virtual machine, if you switch to the primary OS window - the priority of its working applications will be set higher and the CPU resources will be relocated to Mac OS X.
Compressing the Disk Automatically
If you use an expanding virtual hard disk in your virtual machine, its image file size on the physical hard disk increases as you add new data to the virtual hard disk. When you delete some data from this virtual hard disk, free unused space appears on the disk but the amount of space your virtual machine occupies on the hard disk of your Mac does not reduce. To regularly free the unused space back to Mac, use the Enable AutoCompress option. The virtual hard disk in an expanding format will be reviewed twice a day and, if the unused space occupies more than 50 percent of the hard disk image size, it will be compressed and the hard disk image file size will be decreased. As a result, there will be more free space on your Mac's hard disk.
Tuning Windows for Speed
You can make your Windows virtual machine work even faster by selecting Tune Windows for speed. This option disables some of the additional Windows features that tend to slow down the performance of Windows.
To make your Windows virtual machine boot faster, select the Tune Windows for speed option. Some additional Windows features causing system overload will be disabled.
Note: This option is available for Windows XP and later Windows virtual machines.
The Optimize performance for option defines the priority of distributing the main physical computer memory resources:
Optimizing Power Consumption
This option allows you to control the virtual machine power consumption when Parallels Desktop is installed on a Mac laptop computer that is running on batteries (for example, MacBook Pro):
If you select the Enable battery in virtual machine option, the battery status will be displayed in your virtual machine each time your Mac laptop computer runs on batteries. This option is available only on laptop Macs.
If you want to prevent Virtual Machine Configuration from further unauthorized changes, click the Lock icon at the bottom of the window. The next time someone wants to change the settings on any pane of Virtual Machine Configuration, an administrator's password will be required.