Grand Soleil 45' going against the sea

I was surprised to see the performance of my Grand Soleil 45' this summer. We were sailing the Aegean sea, most of the time going upwind. In previous cruises, we learned that she can sail close hauled, in a ground wind as light as 6 knots, and still make about 5 knots.
This summer, sailing the Aegean, We've learned to sail her in much stronger winds. The regular summer winds in the Aegean are strong North winds. Anywhere between 5-9 beaufort is the standard wind in the Agean. So sailing against the wind here is a different story. We learned that we can reef the sails aggressivley (1-2 reefs on the main) and a small napkin on the jib would still take us at 7-9 knots with much less heeling and as fast as with full sails. She can sail as good as 34 degrees to the apparent wind, so we can practically get anywhere with just a couple of tacks.
If the wind is not terribly strong (let's say around 22 knots) we would have two reefs on the main and a full jib. This way we can go really close to the wind but with not much heeling.
We once sailed next to a beautiful 51' Beneteau, in a 12 knot wind. We had just the jib working for us, while the main sail was all the way out (flapping strongly) so the other boat could catch up with us, and we were still making 4 knots, which was faster than the Beneteau with almost full sails up.
The one thing that's less impressive is if you try to motor up wind in high waves. The boat would start jumping on the waves, hitting the water aggressively. We don't like the sound of it, so we just slow down when we go against the sea. I guess that's because she has a flat bow with a vertical ending. The hull works great under sails, but not so well under power.