One major key to stop pinching does involve setup. As previously mentioned, if you have weather helm, your boat will pinch when you're not actively working against that. And, generally speaking, any time you are using the rudder to make the boat go a way it doesn't "want" to, you are bleeding speed (rudders double as great brakes).

The biggest contributors to weather helm are mast rake and rudder rake. You need to experiment to find the best settings for your boat, crew weight and conditions.

Mike