on a recumbent you can't easily decouple your mass from the bike which makes the bike jiggle around less and makes your body absorb a lot more energy; more suspension losses if you like.
A simple way of reducing these losses (potentially by about half) is simply to decouple the body and its contact points from 'the chassis' in terms of vertical movement. The wheels can then ride the bumps without moving the CoG so much and potentially pedalling is not affected.
The earliest example of this approach is the 'the whippet' of 1888
but -despite the obvious benefits on offer- I don't think this approach has been applied to a recumbent machine..... unless someone knows different?