Rereading the first chapter...
Basically, they consider using a "steeper angle of descent", because "gravity will get us there faster". Obviously this cannot be strictly correct, but I was thinking maybe this meant that the ship itself was angled downward, creating a smaller cross-section for wind resistance.
Thing is, I couldn't find a reference for an angle downward. The ship simply falls "like a rock" and is still moving forward from the ethereal web. That's what creates the angle of attack. If this is so, they can obviously decide how much forward motion they have, but I don't see how they can drop faster.