I have a very large c++ project and I'm trying to decrease build times. I've been religious about forward declaring and only including files which are used. However I have many preprocessor defines which are setup in the project files (ie not in cpp or header files) so that I can keep them all in a central location for my different build configurations. Is it possible that this could increase build times? Would moving the preprocessor defines to a header file so they will only be included where needed speedup the build time?
It seems like the build time would be faster if the preprocessor didn't need to scan and replace the defines for files that don't use any of them, but I'm not sure if it's worth the effort.