And, actually, the speed doesn't matter, because the fuel usage of planing hull makes it uneconomic at any speed, even if such speed is greater than displacemen

And, actually, the speed doesn't matter, because the fuel usage of planing hull makes it uneconomic at any speed, even if such speed is greater than displacement hull speed, even though it's infinitely more effective than a displacement hull at those speeds (since a displacement hull cannot reach those speeds basically by definition).