Also, the type of
rig and size of the
jib may factor into what is happening here. I've heard that with a masthead
rig and a large genoa, it is not uncommon for the jib to backwind the main a little. With no battens in the main, the extra curvature may contribute to this. The majority of the main, though, is now in a better position to contribute to forward motion. With telltales on the leech of the main, you can let the main out until they all stream in line with the sail. If there is a bit of flutter in the luff, so be it. The main should usually be eased more than one thinks, hence the common mistake of over-trimming. Just a thought.