One thing I don't think anyone has mentioned is: New sails.
They are the engine of your boat. Unless you have relatively new sails, your's probably aren't performing well anymore. There's a reason the race boats use the best sails and replace them on a regular basis. It makes all the difference, and polars are generally based on optimum sails.
We recently replaced our 14 year old Ulman blue water sails. They were structurally sound but didn't have the correct shape anymore and we were suffering the same, especially with any point of sail forward of the beam. We were motoring a lot when we should have been sailing.
The new sails are North 3DI nordac, which are probably the best cruising sails you can buy (and breathtakingly expensive!). They are built using North's 3DI one piece membrane technology that all their racing sails have been using for the last 5-7 years. They hold their shape much better and for longer than any panel built sail. We are ecstatic with the improvement it made in our boat's performance. We do sail to those polar performance numbers. We are regularly sailing in 8 knots of wind, when we used to wait until we had 10-12 knots before rolling out the sails.
The point of this is not to push the North sails, but show that new sails can make a big difference. There are a number of other quality sail offerings out there that will improve the sailing performance of any boat. If the bottom is clean and you have a folding or feathering prop (we have a Max prop), then sails are the next thing to consider.
Jeff
S/V Journey
Ventura, CA