If performance is your priority then it's more important to choose lightweight wheels rather than looking solely at their size. Also choosing a wider tire which at the same time is designed for performance, (i.e. semi-slicks) will improve your acceleration from a stop. Such factors however will positively affect performance the more power you've got, as it is then that traction becomes a necessity and light weight will help to keep you going faster. So if I were you I would look for lightweight wheels, nothing wrong with 18" if they looked good and I'd pair them with wider performance tires. Technically that should limit wheel spin and still have all the benefits of cornering and braking. You just need to find the right setup for your power for best results. Fuel consumption will increase, nothing you can do about it; performance always costs.
