[gowld]

That's not an answer to the concern. Classical mechanics has no foundation -- it's a large castle floating in the air. Quantum mechanics tries to start from much less less assumed "something from nothing structure", which is puts much more complexity in sight (instead of just hiding it in axioms) that needs to be managed somehow.

If you want purely high-performance model of the Universe, nothing performs better than "everything you observe is simply invented the moment you invent it", be it classical or quantum.