I agree the start-up time is important. There is something that is related. ABCMeta is currently implemented in Python. This makes it slow, creation of an ABC is 2x slower than creation of a normal class. However, ABCs are used by many medium and large size projects. Also, both abc and _collections_abc are imported at start-up (in particular importlib uses several ABCs, os also needs them for environments). Finally, all generics in typing module and user-defined generic types are ABCs (to allow interoperability with collections.abc).
My idea is to re-implement ABCMeta (and ingredients it depends on, like WeakSet) in C. I didn't find such proposal on b.p.o., I have two questions: * Are there some potential problems with this idea (except that it may take some time and effort)? * Is it something worth doing as an optimization? (If answers are no and yes, then maybe I would spend part of my vacation in August on it.)