You experience a long delay when you use any application to create many conferences at the same time in a Microsoft Lync Server 2013 environment. For example, it may take two minutes to create 50 conferences in a Lync Server 2013 environment.
Note Typically, it takes about 20 seconds to create 50 conferences in a Microsoft Lync Server 2010 environment.
This issue occurs because of deadlocks that occur in Microsoft SQL Server. When a server that is running Lync Server 2013 receives a request to create a conference, the Lync server locks the conference table to perform conference replication. If the Lync server receives another conference request from the same user, the SQL Server deadlocks cause a delay.
To resolve this issue, install the cumulative update that is described in the following article in the Microsoft Knowledge Base:
2835432 Description of the cumulative update 5.0.8308.420 for Lync Server 2013, Core Components: July 2013