Take a few minutes and watch: https://windsurfing.tv/video/live-lancelin-ocean-classic-race-winner-matteo-iachino/

Long distance race in Australia. Windsurf winner Matteo Iachino had an avg speed of 39.5 mph
Kite winner Guy Bridge (foil) did 44

Results: http://bluechipresults.com.au/results.aspx?CId=11&RId=1210

The difference just between first and tenth in each discipline is astounding - 12 mph in the kites. While the kite top line honors, the drop off was greater on the kite side - the 5th place kite barely was faster than the ninth place windsurfer - female Karen Jaggi