Thank you everyone for these answers. I think that since this boat is set up for serious racing the topping lift is adjustable via a complicated set of lines up and down the mast and back to the cockpit. I will make an effort to slacken off the lift next time as the main is a very expensive kevlar/fiberglass or some plastic mix that sails fantastically but cost a lot. It would be a shame to wear out the sail through my ignorance.
The fixed boom vang sounds like a great idea, but it's not my boat..
BTW This boat does sail awfully well; better than any other I've sailed in from 14 ft dinghies to a 12 meter.