A new KB hotfix was released today (KB 2797502) regarding graphics update for all the connected RDP clients freezes for at least 100 milliseconds when a client connects that runs Windows 7 Service Pack 1 (SP1) with RDP 8.0 installed.
“…Consider the following scenario:
- You have a Remote Desktop Session Host (RD Session Host) server that is running Windows Server 2012.
- The RD Session Host server has more than 50 Remote Desktop Services (RDS) clients connected, and that causes the RD Session Host server to be under a heavy load.
- The RD Session Host server receives a Remote Desktop Protocol (RDP) session from a Windows 7 Service Pack 1 (SP1)-based RDS client that has RDP 8.0 installed.
Note For more information about how to install and enable RDP 8.0 on a computer that is running Windows 7 SP1, click the following article number to view the article in the Microsoft Knowledge Base:
Description of the Remote Desktop Protocol 8.0 update for Windows 7 SP1 and Windows Server 2008 R2 SP1
In this scenario, the graphics update for all the connected clients freezes for at least 100 milliseconds. Additionally, this issue recurs when the RD Session Host server receives new RDP sessions from any other clients…”
“…This issue occurs because a User Datagram Protocol (UDP) connection object is not created immediately after an Acknowledgement (ACK) packet is received. This behavior provides an opportunity for all the other connections that have a pending date to be sent. Additionally, when multiple connections are established at the same time, if the higher layers of some connections are not ready, a 100-millisecond delay occurs to let the higher layer be registered by using the RDP-UDP layer..”
Source and download: http://support.microsoft.com/kb/2797502/en-us?sd=rss&spid=16526