Our users were complaining of slow startup and logon performance with our Windows 7 fleet.  We got Microsoft in.  One of the things they recommended was deploying two hotfixes:

An update that improves the startup performance of Windows 7 and of Windows Server 2008 R2 is available
Svchost.exe holds a lock on a service when the libraries for the service are loaded. This behavior prevents other services in the same Svchost.exe instance from starting until the call to the LoadLibrary function is returned.


You experience a long domain logon time in Windows 7 or in Windows Server 2008 R2 after you deploy Group Policy preferences to the computer
Issue 1
Assume that you have a client computer that is running Windows 7 or Windows Server 2008 R2 in a domain environment. You deploy Group Policy preferences (GPP) to the client computer by using item-level targeting using security groups. In this situation, a user of the client computer experiences a long domain logon time. This issue becomes more noticeable if the domain controller is only reachable over a slow link.
Issue 2
When you apply GPP by using item level targeting for security groups, local ports are leaked in an OPEN_WAIT state. After some time, the nonpaged pool is depleted and the computer stops responding.

They both worked very well in our environment.