I ride a couple of 'bents regularly... my bikeE CT is a semi recumbent model that is not designed for speed but it ticks along pretty easily at 30kmh / 18mph on the flats and like a previous poster.
The Catrike is a different beast and I have run laps in the park loop where roadies and tri geeks train and strain and have no problem keeping up and usually overtake and pass them since the bike is considerably more aerodynamic and requires less wattage for a given speed.