Help, theory, experience
Last year i've spoken to Alex Sandri - who told me that the render time (he uses mental ray) depends on the geometry in terms if there are all quads it will be faster VS. trianglulated geometry (other software/booleans etc)
Now i'm in need to write another science paper and only topic from 3D that's coming to mind is this - render time in terms of scene geometry
Googling for this type of information seemed impossible and it is as it turned out.
So if anyone has any idea, info, theory or has done some testing i would like to hear it.