Here is a Brad Gilbert drill to help build speed...
Assume your normal serving position but, rather than positioning the racquet in front of you, start the racquet in the "L" position (pre back scratch). Toss the ball as you normally do, then drop the racquet to a full back-scratch position and proceed with the hit.
I know it seems counterintuitive that eliminating the take-away and starting in the "L" position will demand that you increase racquet speed in order to make correct contact with the ball, but it really does work this way (probably due to the elimination of the initial momentum).
Hope this helps.