My bikes range in weight from 20.5 to 50 pounds... road and mountain bikes are the light end of that scale while the utility bikes are at the other end... my extra bike weighs 50 pounds before anything goes on it but as I can get fairly low and aero I can ride at a fairly decent pace. A lighter bike with a more upright riding position would not offer much of a benefit due to the added wind resiostance.
The biggest difference in performance comes from how aerodynamic a bike is and weight is secondary until you are climbing and even then, a few pounds does not make a noticeable difference unless you are racing for money.
Like a car, the unsprung weight has the most effect on performance as lighter wheels and tyres can really change a bicycle.