This post isn't directly about racing, because what I discovered was under motor. However it sure is about "performance" in the below hull speed range.
I have a new motor (see here) and when I was testing it recently, it got up to 3.0/3.1 knots on my GPS in flat water under bare poles and a slight breeze off the stern quarter.
My crew was steering with the tiller, seated just about where the mainsheet block is located. By standing up on the cuddy, I was able to make the boat go faster, the GPS read 3.2/3.3 with an occasional 3.4.
I think this difference is entirely due to the different fore/aft balance and not, say, to my body acting as "sail". That would mean that in those conditions, the fore/aft balance is super critical. If most of you are like me, the wide expanse of bench going all the way to the rear is always tempting (and crowding the crew at the front of the boat doesn't always feel comfortable). But not moving all the way up comes at a cost.
On occasion, I will have to rerun this experiment to see whether ordinary weight distribution inside the cockpit is enough, or whether the effect requires one person to be on the cuddy. That would not be practical for races under class rules (but would be fine for the some of the no-handicap, more relaxed events I sail in during the summer).
Anybody else have any data or experience?