When Darcy says “but it is a subject which always makes a lady energetic.”, I believe he is being condescending. He might find Elizabeth attractive, but he still seems to hold her for a simpleton.

Elizabeth tells Darcy a saying ('Keep your breath to cool your porridge') specifying that everyone HERE is familiar with it. She seems to imply that he is not familiar with it, but should be. She refers the saying to herself – she will stop talking and sing instead, but could the she imply a double meaning? Could she mean that Darcy should have kept his mouth shut and danced instead at the Meryton Assembly?