Its significant in terms of both speed and energy output by the rider. I once rode a century on a hybrid - bought a road bike a month later and have never been sorry. Lack of multiple hand positions and aerodynamics are the culprits IMO. I realize that many people ride the hybrids over long distances all the time, but I believe they are best suited for MUP;s, commuting, etc., with moderate mileage. The fact that they are hybrid indicates that they are a compromise between road and trail, and don't function as well in either environment as a bike specifically designed for the job.