Could the Boeing 747's 'hump' be improved aerodynamically?
The 747-300/400 has a longer hump than the original 100/200. Surprisingly, this longer hump had lower aerodynamic drag than the 200 hump: at higher mach numbers compressibility starts to cause serious drag increase. The speed at which this "drag divergence" occurs depends on the variance of cross section area of the plane. If the cross section of the plane would be a constant value, drag divergence speed would be closest to mach 1.

The longer bump on the 747-300 resulted in a more constant cross section and therefore higher drag divergence number => higher cruise speed.

Could it be made more efficient aerodynamically? Yes, by trying to match the Area Rule as closely as possible.

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