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.