We have a large Visual Studio 2005 C++/Mfc solution, 1 project with around 1300 source files (so about 650 .h and 650 .cpp files). We also use Boost and a few other librarie
I'd have to agree with Goz, take a look at this (SO) post to see ways to help remove redundant header files.
Our C++ solution is of this rough size and used to take us 50 mins to compile, by careful header file analysis, we got that down to 8 mins.