Precompiled Headers
Precompiled headers are what their name suggests- sections of a game that are precompiled. This way, each time someone compiles a new build, it doesn’t take quite as long as it would to compile the entire thing. Mostly, this is a legacy feature from when computers were much slower, where a single full compilation could take dozens of seconds or even several minutes.
As it is not even recommended to compile your final build using precompiled headers (as the game will be bulkier and less memory-efficient), we won’t reiterate how to compile them here. Rest assured, it’s all covered in The Hugo Book if you are in need.