Default power options in Windows 2012 Server control panel may impact performance.
Set your power plan to High performance to increase processor performance (in Control Panel > All Control Panel Items > Power Options > Preferred plans).
For more information, see Using power plans in Windows Server at http://msdn.microsoft.com/en-us/library/windows/hardware/dn567635.
http://msdn.microsoft.com/en-us/library/windows/hardware/dn567635