Slow loading of solution/project with multiple configurations

Loading a project with multiple configurations (only a different preprocessor defined OEM name) is slow.
My standard project has build configurations for 12 OEM's, debug and release and has about 30 moc_*.cpp generated files.
Loading the project takes about 50 seconds. If the corresponding .suo file is removed the startup is normal again. (will be generated again).
Without the qt vs addin the loading is also normal.
Attached are two solutions (multioem.sln and singleoem.sln). Switch between both solutions and in my case there is a noticable loading time difference.