I found the explanation defining
WIN32_LEAN_AND_MEAN "reduces the size of the Win32 header files by excluding some of the less frequently used APIs". Somewhere else I read that it speeds up the build process.
So what does
WIN32_LEAN_AND_MEAN exclude exactly? Should I care about this pre-processor directive? Does it speed up the build process?
I've also seen a pre-processor directive in projects named something along the lines of extra lean. Is this another esoteric pre-processor incantation I should know about?