There are a number...
...of things you can do to increase light air performance. Not the least is a super clean smooth bottom and a feathering prop. Your main needs to be able to get very flat. A baggy blown out main cannot keep flow attachment robbing boat speed. Move all the crew to the leeward side of the boat to induce sail shape and decrease wetted surface area. Do not choke the genny. Move the car slightly forward and crack off on the sheet to allow the genoa to breath.Remember that pointing in very light air is just not efficient. Sail a little low and build apparent wind speed. The boat will slowly accelerate.