well the key to keeping speed on flats is the frech fry method. You must be doing the reverse pizza, your gonna wanna straighten your skis out like french fries. That is the secret to keeping speed on flats.
You have to assume that will happen when riding switch, so either start higher up and dont speed check or ski most of the way to the jump forwards and in the last 50ft just jump and do a revert into switch and that should help you carry speed better. Also try and keep your skis really parallel when you ski switch.