Marc-Andre: Oh, I know. I proselytize to coworkers on the virtues of using __slots__ for classes that will have many instances created (particularly since entirely too much of our stuff is still Py2.7, so we don't have the "free" savings from shared key dictionaries). Heck, I particularly enjoy inheriting from an inlined collections.namedtuple and an empty __slots__(which does add 8 bytes to the size over declaring the __slots__ directly, but gets you as close to truly immutable instances as you can get when you need them, not just "we're all adults here" immutable instances).

I'm just pointing out that if he thinks 56 bytes per object is too large, he's going to be disappointed with what Python has to offer. General purpose user-defined Python objects don't optimize for low memory usage, and even __slots__ only gets you so far.