To answer the OP's question, I read back when gas prices syrocketed that the airlines had instructed to pilots to fly slower. Not much, but a little. It added about 30 minutes or less to a NCY-CDG flight, as I recall.

With gas prices lower now I would guess there is a benefit to getting the planes there faster -- lower labor, cost of equipment use, etc. So they may have speeded back up. But they can and do slow down to save on gas.