Summary
VS2010 or msbuild v4.0 builds are excessively slow compared with earlier versions and each job takes over 15 minutes irrespective of the project size.
This occurs because msbuild v4.0 does not exit immediately after a build for performance reasons. Therefore eMake must wait until the default 15-minute timeout has elapsed before continuing.
Solution
Set MSBUILDNODECONNECTIONTIMEOUT=0. This sets the length of time (in milliseconds) that msbuild will linger before exiting.
Alternatively, you can set /nodereuse:false as an msbuild parameter.