Yep, all of this is good advice but requires being able to change the code, which is far from a given in c++ where you may have to work with a dozen proprietary

Yep, all of this is good advice but requires being able to change the code, which is far from a given in c++ where you may have to work with a dozen proprietary SDKs. I personnally use clang -ftime-trace to see which headers take the most time and then Qt Creator's "find all places where this file is included" feature to try to make the most efficient cleanups