I'm surprised nobody here has mentioned frame geometry/body position while on the bike. Hybrids give a more upright position, which will not be good for high speed due to wind resistance. I've got a Trek 7.3 (hybrid) and Jamis Ventura (road). While each has its own positive and negative points, I can achieve and sustain a much higher average speed on my road bike due to being able to get aero on the hoods and drops. You encounter a lot of wind resistance relative to power output much, much faster on a hybrid.