It is not lens distortion and it looks even more impressive when looked at from the boat. As to why it might be fast, there are a couple of things I've thought or read about. The DN is pretty over canvased so with stiff masts when a gust hits, it pops into a high hike and the sailor is forced to dump power, etc. to get back down. Bendy boats just accelerate through the puff with much less drama. Also there is no mast rotation limiter on a DN. Stiff masts could over rotate at high mainsheet tension which turned the mast 90 degrees to the sail completely boarding out the sail except for the 4" mast now sideways to the air flow. This is not a fast shape. The bendy masts stay in line with the sail better making for a much faster shape. But why is it only done on DNs?