if it's performance you're worried about, for programs that don't care about width, i'd expect 32 bits at least
to match performance with 64 bits (if there's a measurable difference). for one thing, cache lines will contain

more values, and several will be fetched at once when cache lines are filled.

And for programs that do care about this, C99 provides things such as int_fast64_t (which IIRC 8c et al does not currently support). In a way, expecting something out of 'int' is sloppy, despite it's wide use.