The thing is the prototype X35 for the F35, b or not, took off in less than 150 mts, and expected ground runway for the F35b is +-165 mts. and that is for ground take off, ie expecting sometimes wind in favour or the contrary, so like in general 165 mts. for taking off if the ship is stopped, that is similar situation to a ground runway with no wind.
So that ship, in carrier mode was 24000 t. for 24 knots max sustained, for Canberras. Even in sea trials the propulsion exceed a bit the expected speed. So you can expect in any config wheter 24000 t. or 27000 t. you have +20 knots sustained speed, that is like 35 kms/h.
So that if the F35b reaches the required speed for taking off from 165 mts with 0 knots, now with the +20 knots the jet will need less than 165 mts, and with the sky jump still less, luckily you could launch the F35b ocuping just 4 spots.
In the sense that for Stovl jets, the speed from the carrier it is not that important wrt Catobar ones. I wouldn´t say that in action the normal cruise speed is +20 knots for fleet oilers and other ships, together with their submarines. The faster you go, the more noise you make and consume fuel, reduce endurance etc.:eek