To resolve this issue, install the November 2015 cumulative update 6.0.9319.102 for the Microsoft Skype for Business Server 2015 Response Group service.
Note After you install this update, you must update the Transact-SQL query by running LyncUpdateInstaller.exe, and then run the following command in Lync Server Management Shell:
Install-CsDatabase –ConfiguredDatabases –Update –SqlServerFqdn sqlserver.domain.com
Note This update includes performance improvements for the response group usage Transact-SQL query in Microsoft SQL Server 2008, Microsoft SQL Server 2008 R2, Microsoft SQL Server 2012, and Microsoft SQL Server 2014.
This issue occurs because the Transact-SQL query takes too long to complete or times out.