When stretched out
More than likely sails that are 20 years old, even on a boat with less than average use, will be stretched out and baggy. The draft in the sail has moved so far aft that they no longer give much power to the boat. The boat will still sail, but you probably don't have anything to compare the performance drop off until new sails are made and you sail with those.Then you will probably say "WOW" didn't know my boat could be so easy to sail, so fast and with a lot less heel.Contact a local sailmaker, he can come out to your boat, evaluate your sails, show the good the bad and the ugly about them and quote you a price to upgrade to new ones.Good luck.