One of the best ways to control your speed is to get out of the rut. Gernot isn't the first instructor who tried to pull me out of the trough. I took that as a compliment-but she didn't intend it as one. You need to ski the bumps in a way that you'll be able to keep up for a long time. She suggested shaving off speed by sliding down along the side of the bump.
Most bumps are oblong, like a whale.
She said she thinks of the motion as sliding down the whale's side and tickling its ribs. This involves staying out of the trough altogether by skiing along the ridges formed by the tops of the bumps. Which is why flexibility is so important while skiing the bumps. When I followed Gernot down the slope, he went along the top of a couple bumps, down the side of one and then into the trough for a couple turns. He was living the dream, deciding where he wanted to turn and then adjusting to the terrain accordingly.