I promise you incremental builds are extremely important. A completely clean build of iOS/OSX years ago would take multiple days & I'm sure it's only gotten worse. The entire internal CI system relies on incremental builds working properly so that they can generate an internal iOS build every day for testing. It's possible it's disabled for certain projects but I doubt it. C++ in no ways alters the incremental build mechanism; all the problems of incremental builds it inherited from C's preprocessor. Speaking of, that's what C++ modules fixes (clang has support for C & C++ there although when I left only C projects had it on).