On: Make LLVM Fast Again

[NCG_Mike]

A couple of things a C++ developer can do is to put template instantiation code into a .cpp file, where possible.

"#pragma once" in the header files helps as does using a pre-compiled header file.

Obviously, removing header files that aren't needed makes a difference too.

[brandmeyer → NCG_Mike]

`pragma once` doesn't do anything that a well-written header guard does.