Exactly. Essentially this reduces the algorithmic complexity of compilation which is a huge boon given that even simple programs these days result in the (repea

Exactly. Essentially this reduces the algorithmic complexity of compilation which is a huge boon given that even simple programs these days result in the (repeated) parsing of millions of lines of code. Instantiation of templates obviously won't change, but recursive traversal and repeated re-parsing of includes will be completely unnecessary as the compiler can trivially[1] cache the intermediate version. Which is as it should have been from the start, but then hindsight is 20-20. It's really an elegant solution considering the constraints they're working under. [1] Preprocessor macros don't leak from includers to includees, so headers become independent of each other.