A superintelligence isn't a genie or magic wand ... it can't make a computation that cannot be completed in a feasible amount of time run any faster. This is precisely what makes systems chaotic--they are fully deterministic but not predictable in a timeframe shorter than their execution.

And no, nothing has to compute the universe ... e.g., the path of the Earth through space can be computed, but it will follow that path as a consequence of the forces acting on it whether it is computed or not.