The goal of this article is to give the reader an estimate of the relative impact that the Microsoft Lync 2010 desktop client has on the Microsoft Exchange 2010 Client Access server. This estimate can be used to determine the Exchange Server resources required to design a new or expand an existing Microsoft Lync Server 2010 deployment.
Read more at source: http://blogs.technet.com/b/nexthop/archive/2011/06/30/understanding-lync-2010-client-scaling-and-workload-impact-on-exchange-2010-client-access-server.aspx
Cheers,
Anderson Patricio
http://blogs.msexchange.org/patricio
Twitter: @apatricio