Yesterday Microsoft issued a bumper of a update for the Lync 2013 client build April 2014.
This update will soon form part of the office update suite but for now its available via the MS download page here.
http://support.microsoft.com/kb/2880474/en-gb
The update is a good one with lots of code fixing within it.
2941631 Cannot drag a distribution group to change position in your contact list in Lync 2013
2941639 Call forwarding to the Response Group fails in Lync 2013
2941640 Desktop sharing session stops in Lync 2013 when all screen data is updated
2941643 Caller cannot close the window of a transferred call in Lync 2013
2941654 Update sorts and searches contacts by Furigana in Lync 2013
2941658 CTRL+TAB does not work when you switch between conversation windows in Lync 2013
2941682 Instant message appears using incorrect text format when the DisableRTFIM setting is enabled in Lync 2013
2941659 Callee’s name and detailed information is missing from the conversation history of a Lync 2013 outgoing call
2941636 Search fails in Lync 2013 when non-Latin characters are used in a different case from the AD DS attributes
2941635 Can’t sign in to Lync 2013 when Office 365 account UPN differs from domain account UPN
2954951 Slow screen update in application sharing or desktop sharing session in Lync 2013
2955577 Lync 2013 takes a long time to sign in after reconnect to the network
2955579 Lync 2013 displays un-encoded texts in a toast notification or an instant message sent to another messaging client
2955580 Update adds a button to show details about limited functionalities when Lync 2013 connects to a backup pool
For me there are a couple of interest. And these are
Fixed calls failing when forwarding into a response group.
And the reconnect time taking a long time.
When you putting the update on ensure you have met all the prereqs detailed within the information of the download page.