Precompiled headers are a pain to use. But clang modules are supposed to be precompiled headers done right:

http://clang.llvm.org/docs/Modules.html

When they're usable for C++, there should be little reason to use any special preprocessor, since every header file (not just a static common set) need only be compiled once into a binary format rather than being included into N source files. It can't happen any sooner for me... but as of recently, they're still very broken, so I'm still waiting.