Skype for Business client becomes unresponsive when you join a meeting with lots of participants

Symptoms

Assume that you're running one or more Lync SDK–based applications on your computer, and you join a meeting that has a large number of participants. In this situation, your Lync or Skype for Business client becomes unresponsive for a period.

Cause

Joining a meeting with a large number of participants generates thousands of internal events, which are then queued and processed.

The presence of a Lync SDK–based application causes the Lync or Skype for Business client to send these internal events to additional queues. These queues use inter-apartment COM calls that take significantly longer to complete. While this queue is processing, the client UI becomes unresponsive until the queue is cleared.

Workaround

To work around this issue, exit all Lync SDK–based applications before you join a meeting.