Please excuse my lack of knowledge here: these may seem like stupid questions but I know very little about road bikes. Although I understand the basic mechanical differences between these bike styles, I don't understand the difference in performance between the bikes. I imagine the hybrid bikes to be essentially 'slower' than road bikes due to the gearing, tire width and in some cases the frame. Am I on the right track?
I have a hybrid and a mountain bike and have ridden only on the streets for quite a while. The hybrid with thin Ultra 2000s is significantly faster than my mountain bike with 'city slicks', although I am unable to reach the avg mph on the hybrid that most people report as a 'moderate pace' on their road bikes. I am wondering if by switching to a road bike, I might see another significant increase in performance (?). Or should I just pedal this thing harder?

It's hard to tell... my hybrid seems about equal in weight to many road bikes and I was able to pick up a little more speed when I added drop bar ends.... I guess what I'm getting at is this: should I be able to expect the same performance from my modified hybrid as I could with a road bike? Thanks for putting up with my rookie questions.