As part of the full Office 2013 update dated November 11, 2014 (See here for full details), Lync 2013 clients gets an update as well, KB2899507.
The update fixes the following issues:
- Video freezes consistently for two second-intervals when you make a video call in Lync 2013
- Incorrect format of string in a trace statement when application sharing session viewers stop viewing in a conference
- Memory leak occurs when you start a peer-to-peer application sharing session in Lync 2013
- Lync 2013 crashes when you join a meeting that is hosted on Lync Server 2010 as an anonymous user
- Lync 2013 freezes when a toast notification of a call appears
More information here.