[CMake] VS2012 builds using v3.1.0 are a lot slower than v2.8.12

[Yves Frederix]

Hi all,

I recently made the upgrade from v2.8.12 to v3.1.0. Unfortunately, I
am now experiencing a serious decrease in build speed for the VS2012
Win64 builds. I have searched the cmake mailings but I was unable to
find a reference to a similar issue.

To give an idea about the difference I am observing: a full build
(Release, Win64, "cmake --build") using 2.8.12 takes about 7 minutes,
while for 3.0.1 it takes 24 minutes to complete the same build. Both
builds are based on the same settings (some compilation settings are
specified explicitly by our own scripts, but not that many), which
gives the impression that the difference might be due to a change in
default compilation settings generated by cmake for the Visual Studio
generators since 2.8.12. Might this be the case? And if so, what might
be a solution?
If more information or tests from my end would be required, please do
not hesitate to let me know as I am certainly willing to dig a bit
deeper into this!.

Thanks!

Best regards,
Yves