Even reduced headers will take longer to compile than with one precompiled header.
What is if you use more than one library?
Well, in my project I have one main include including everything else, and precompile that whenever any of my headers change. Thus no problem with the flags or using multiple libraries, and fast compiles despite C++.
I've uploaded a fixed archive. I tried to build the source based on the coding style of the scenenodes included in irrlicht. Out of that view it is correct to reduce headers (Every scenenode in irrlicht is coded that way). Also it would be correct to replace the #define with with a static uint (I did not find any scenenode in irrlicht using a #define). On the other hand in my projects I act like hendu (using precompiled header). So in the end it depends on the coding policies (like naming conventions too).... Nevertheless thank you for the hints and the comments!