Generally speaking, the advice here is generic to all sailboats.
If you are looking to spend some money making your boat go faster, spend it on good quality sails. To get the best performance from your new sails you should have some easy to adjust hardware such as a main sheet system with traveler, outhaul, cunningham, boom vang, backstay adjuster, adjustable genoa leads to name a few. Expect to spend a few thousand dollars on these items.
However, if your crew work is marginal, no amount of money will put you at the top of your game. You can gain many positions in the fleet by practicing and that won't cost you more than a few beers. Boat preparation such as the smoothness of your bottom, the fairness of your keel and rudder, the tuning of your rigging and the calibration of your instruments all add up to a winning season. And don't forget good tactics because sailing on the lifted tack can overcome deficiencies in other areas. Learn how to trim your sails properly for varying conditions and keep notes of what works best. Read, talk with other racers and crew aboard as many competitive boats as you can. You'll never stop learning this sport.
Your question is broad so it would be helpful if you can give us some clues as to the general areas of your boat that you want to improve upon. We'll be able to give you more specific advice germane to that area. I'm up for a short winter too.