Peter Levy did you find an answer to the question? we are also having similar issue with one of the application and I noticed the c/c++ runtime msvcr80.dll consuming all the activity.
on Windows 7 the dll was invoked 11 times and consumed like 1.5 minutes
on Windows 2012 server the same dll was invoked 26 times and consumed like 10.x minutes
on Windows 2008 R2 the same dll was invoked and consumed same as Windows 7 but the overall report generation seemed slower.
any help will be appreciated :-)