In light winds, try to take advantage of gusts and wind shifts. You may find yourself tacking more often, which slows the boat, so use roll tacks. In roll tacking, the crew weight and the forces on the boat are used to your advantage, resulting in more efficient performance. The rudder resistance is reduced as the rudder is being used less to turn the boat. Roll tacks reduce the drag and deceleration as the boat turns upright and the sails flap, generating air resistance.
By rolling the boat with your body weight, the sails are fanned through the air, keeping them full for longer and dragging less. In this way the airflow is reattached to the sail quicker after the tack.