He never specifically said it's C++ nor Java. I think he's talking about C++. C++'s slow compile problem has to do with the repeated inclusion of header files

He never specifically said it's C++ nor Java. I think he's talking about C++. C++'s slow compile problem has to do with the repeated inclusion of header files for every source file, which can become a FileNum^2 recompilation problem. Though pre-compiled header files and refactoring into pre-built libraries should reduce the compile time. Java simply does not have the slow compile problem due to its simple package/class per dir/file, where a compiled class won't be recompiled again.