The best advice I ever got to playing fast was to practice in bursts.

Take your favorite lick and cut it into segments of 3-5 notes. Then practice each segments in bursts. Concentrate on accuracy (if you want to play malmsteen you'll need it).

When you can play tow segments really fast in burst, join them together and practice again. This is a long process but it will give you more speed.

You can't expect to do gain speed doing a 30 notes run up and down and keep your accuracy. (Well I can't). Just learn segments and paste them later.

Another method is to take the first 5 notes, practice in burst, and then add one more note. When you master 6 notes then go to 7 notes.

Practice with a metronome is also good improce your skill. It's good to be fast but it's better to be fast in tempo :)

Try it and tell me what you think.