I guess I'll break from the pack a little bit here. On tacking I've found that one of the ways to kill acceleration is by trimming the jib hard before the main. Being too agressive on the jib while the main is still slacked can affect the flow on the back of the main - slow, slow, slow. The jib needs to trimmed for sure to keep the boat from roundng up after the tack, but it should initially be trimmed to less than its final upwind trim. The main is the bigger sail, keeping it breathing gets you moving (but there also needs to be balance). As the boat accelerates, trim the main and then get the final trim on the jib, or trim them together. Going heavy on the jib first will close things off. Every time I've had a tack that we were slow coming out of either I didn't steer far enough through the tack, or the crew did final trim on the jib before we were up to speed.