When many legacy presence users are converted to enhanced presence users at the same time, you experience performance issues in Microsoft Office Communications Server 2007 R2. These performance issues may include the following symptoms:
- A heavy load occurs on the back-end server that is running Microsoft SQL Server.
- Users who are logged on are logged off.
- Most end-user scenarios such as instant messaging, presence, conferencing, and audio/video calls are unreliable.
Legacy presence users use Microsoft Office Live Communications Server 2003, use Microsoft Office Live Communications Server 2005, or use Office Live Communications Server 2005 Service Pack 1 (SP1). Enhanced presence users use Microsoft Office Communications Server 2007 or use Microsoft Office Communications Server 2007 R2.