Yeah Karl, Have to agree with the two answers so far, seems weight helps hold down more sail area, making you faster. Common for the guys trying to break speed records to wear weight vests. When the wind is up to 30knots I am down to 5sqm sail, at 72kg. These guys are using the same size sail in 50knots plus. There is also some serious skill involved.
The first day at last year`s Defi Wind in France was over 50knots, the organisers allowed only the pro sailors to race, to put on a show. This link is to the video..
http://www.youtube.com/watch?v=HGgFuxHExYo