By default, GPO processing is synchronous, which means that the processing of one GPO must be complete before processing of the next one begins. Computer Configuration policies apply at system startup, and User Configuration policies apply at logon and complete prior to the user interface becoming available to the user.

In most cases, you’ll want to continue to use the default synchronous behavior. You can, however, configure Windows Server 2003 to process policies asynchronously. With asynchronous mode, GPO processing can occur simultaneously and on multiple threads, providing better performance and faster processing. To ensure reliable application of policies — particularly where certain policies need to override policies set at lower levels — you should use synchronous mode. Use asynchronous mode only when performance is an issue, and then use it judiciously.

You configure GPO processing mode through the Default Domain Policy. To do so, open the Active Directory Users And Computers console. Right-click the domain and choose Properties. When the Properties window appears, choose Default Domain Policy and click Edit. Next, Expand the Computer Configuration/Administrative Templates/System/Group Policy branch. Double-click the Group Policy Refresh Interval For Computers policy, click Enabled, and then set the interval and the offset range. When finished, click OK and close the Group Policy console.