Both drag and lift depend on the speed of the airplane relative to the wind, not relative to the ground. So, if the maximum efficiency dictates that the airplan

Both drag and lift depend on the speed of the airplane relative to the wind, not relative to the ground. So, if the maximum efficiency dictates that the airplane should travel at speed X relative to the wind, and the wind is flowing at speed Y in the same direction as the airplane needs to travel, then the airplane, flying at maximum efficiency, will be travelling at speed X+Y relative to the ground.