The “Slow network connection time-out for user profiles” Group Policy setting does not work for a Windows Vista Service Pack 1-based or a Windows Server 2008-based client computer
In a domain environment, you configure the Slow network connection time-out for user profiles Group Policy setting to reduce the time that is required for roaming profile users to log on to the domain through a slow network connection. Assume a user then logs on or logs off the domain through a slow network connection from a Windows Vista Service Pack 1 (SP1)-based or a Windows Server 2008-based client computer. In this scenario, the time that is required to log on or to log off the domain is still longer than expected.
Note: After you configure this Group Policy setting, you expect the roaming profile client to use a local copy of the profile if the network connection is slow.
If you check the user environment debug log or if you capture a network monitor trace, you see that the client computer downloads or uploads the roaming user profiles every time that the user logs on or logs off the domain. This behavior occurs even in a slow network environment.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB957802.