Apply Group Policy for computers asynchronously during startup
Computer Configuration\Administrative Templates\System\Group Policy
Lets the system display the logon prompt before it finishes updating computer Group Policy.
If you enable this policy, the system does not wait for Group Policy updates to complete before inviting the user to log on. As a result, the Windows interface might appear to be ready before computer Group Policy is applied.
If you disable this policy or do not configure it, users cannot log on until computer Group Policy is updated.