Since weight only affects power required linearly with speed, that's where you want to compromise if you want to go fast on flat ground or downhill.
My guess is that aero wheels with three really wide "spokes" (more like wings) will have the least amount of drag, without much of the sidewind problem solid discs have. Given the relative unimportance of weight for top speed, they could very well be made strong enough to match a spoked wheel in terms of strength and durability, and still be much faster.
Like this: