Abstract: A lightweight, high speed roll-up door, or curtain, is unrolled from and rolled upon a cylindrical tube disposed above or within an opening in a wall by a drive motor/drive shaft combination coupled to one end of the tube. A non-rotating support shaft is attached to the other end of the tube which has disposed within respective ends thereof first and second coiled springs. A pair of belts are coupled to lower opposed ends of the door and are wrapped around respective pulleys positioned at each end of the tube and mounted to the drive and support shafts, respectively. With one end of each of the coiled springs coupled to the tube and each of the other ends respectively coupled to one of the pulleys, the coiled springs urge the two pulleys and the tube in opposite directions of rotation to maintain the door in a tightly stretched condition.