making octaves fast

[joeplaysthepiano]

I've been practicing chopin's nocturne op.48 no.1 for a while now and I have almost everything down except I would like to make the octave cadenza as fast as possible.  I can play the chromatic run downward fast, but the beginning passage that goes c-d-c-g-a-g-e-f-e etc. downward in octaves is difficult for me to play as fast as I would like.  Any advice on how to practice this and make it faster (without sounding choppy too) would be greatly appreciated

Thanks, Joe

[bitus]

you should play over the keys from your arm... practice it slowly by moving the arm to the next key before playing it and only when you arrive at the key, then play the octave. After a while, you will automaticly move your arm, not your hand. This will make it much easier to go fast.
The Bitus.