CPU usage increases when you turn on tracing for the S4 component in Microsoft Office Communications Server 2007 R2.
This issue occurs because tracing for the S4 component uses the INFO trace level. This trace level turns on verbose tracing, which causes the increased CPU usage that is mentioned in the "Symptoms" section.
To resolve this issue, apply the following update:
977351 Description of the cumulative update for Office Communications Server 2007 R2, Unified Communications Managed API 2.0 Core Redist 64-bit: January 2009