As explained in PEP 560, creation of Generic subclasses is much slower (~7x on my machine).
My guess is that a limited number of applications actually need Generic classes at "production" runtime (i.e. when not under analysis of mypy or IDE).

I propose a special class that will alias typing.Generic whenever typing.TYPE_CHECKING == True and a no-op stub otherwise.


Best Regards,
Ilya Kulakov