Why are windfoils so slow? The overall 500m speed record is held by a foil, Sailrocket, at 65 knots. Kitefoils can go 45 knots...so why are windfoils so slow at 35 knots when a conventional windsurfer with a fin is averaging 53 knots over 500m.

Windfoils are great in light winds and very efficient but once the wind is above 15 knots windsurfing is quicker. What's holding the windfoil back, can it be overcome and how fast can they ultimately go.