Yes, you need to ride at least 1,000 miles before you will be efficient. Three things helped me increase my speed on public roads:

(1) Learn to make right hand turns (e.g. at a stoplight without stopping). You should be able to do this while staying to the right of the white painted line.

(2) Shift into first gear before the wheels stop. Always.

(3) Shift only into the next gear. By this I mean, if you're in third gear (the third lowest), shift only into second gear or fourth gear, depending on your circumstances.

(4) Shift both deraillers simultaneously.