One could argue that heavy-displacement vessels already have a certain amount of performance designed out of them, therefore the performance difference from weight changes is less noticeable. When looking at SA/D, which doesn't tell the whole story but is a performance metric we all understand, we expect lighter boats to perform better, all else equal. As for weight distribution fore/aft, that is largely a function of hull form and waterline... For example, if you load up the back of a boat enough so the hull "squats" there is likely to be more turbulence and therefore more drag at the stern. A heavy bow is likely to plow heavier into waves and sit deeper, also causing more drag. And of course we all know that weight located in the ends is less desirable than the same weight low and centered, for many reasons.

That's why I choose to carry the dinghy on the nets. It places the weight near the fore-aft center and although it's off the centerline, it's only about 72 pounds (not a major issue). In the picture it's upright (drain plug removed) because we were in Block Island Sound in fair weather, but if we were expecting storm conditions or even high winds we would flip it over and makes sure it's well tied. If going offshore I would consider deflating it (for less windage) and stow it inverted on the cabin top beneath the boom, so it would be less likely to caught by boarding wave crests.

Weight aloft vs. carried low (or weight saving aloft) is another topic.