Agree with Tim. If you think you are slow becouse of ${insert any reason you like here} you do sail slow. The mental aspect of sailing is way underrated and people look for excuses all over the place instead of identifying what they did wrong and fixing it. Once the basic skills are developed, it is your own negative feedback loop (the "blame game") that hampers your development as a sailor.
I guess it is human, but it is not performance enhancing.
As long as the boat does not sink under you, get out there and race. Bugger optimum weight until you are a medal candidate at the Laser, Finn or Star worlds.
Rolf:
The later Carlton Tucker said a lot. "Get you head out of the boat" As you said we need to think what we need to do to make us better, not try to find blame why we didn't do the right thing at the time. I agree with you 100%. I won a LOT at heavy weight (315-320 when everyone else was around 295-300) when I first got started by learning boat handing taught to me by my "A" fleet H-16 crew and TIME on the water!!!!
Doug