Have you noticed that it was easier to hoist your mainsail when it was new? This may be because the luff hardware (typically metal or plastic sliders or slugs) has become worn or deformed, causing excess friction. Chris Caldwell of Piranha Sails in Marblehead, Massachusetts, has a neat short-term solution thats as simple as making a quick stop at the supermarket for a bottle of dish detergent. He uses Lemon Fresh Joy for his short-term fix, but any similar product will do.
Detergent in hand, you then go up the mast and apply the stuff to the mast track; on a small boat you can apply the detergent to each slider by hand without going aloft. It will wash off, of course, but its fine for a quick fix; dedicated marine lubricants last far longer. Both work equally well on extruded headsail foils.