Long logon time when you establish an RD session to a Windows Server 2008 R2-based RD Session Host server if Printer Redirection is enabled

Microsoft released a new KB article today related to long logon times on a RD Session Host based on Windows Server 2008 R2 in situations where Printer Redirection is enabled.

Article ID: 2655998 - Last Review: February 15, 2012 - Revision: 1.0
Long logon time when you establish an RD session to a Windows Server 2008 R2-based RD Session Host server if Printer Redirection is enabled

Consider the following scenario:

• You have a Windows Server 2008 R2-based Remote Desktop (RD) Session Host server in an Active Directory domain environment.
• You apply the Printer Redirection Group Policy setting to RD sessions that connect to the server.
• You repeatedly establish RD sessions to the server from a client computer that has multiple printers installed.

In this scenario, the logon time increases every time that you establish an RD connection. Additionally, the % Privileged Time count increases in the Svchost.exe process that hosts the User-mode Plug-and-Play Service (Umpnpmgr.dll) on the server. This behavior occurs every time that you log on, log off, or reestablish an RD session.

This issue occurs because the Remote Desktop Services Device Redirector service creates a new port every time that an RD session is established. However, the inactive ports are not recycled. Instead, the inactive ports for the redirected printers accumulate under the following registry key on the server: KEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceClasses\{28d78fad-5a12-11d1-ae5b-0000f803a8c2}\##?#Root#RDPBUS#0000#{28d78fad-5a12-11d1-ae5b-0000f803a8c2}\

Source: http://support.microsoft.com/kb/2655998/en-us?sd=rss&spid=14134