I have been alternate picking for awhile but have not been able to get up to speed so to speak, so recently I bought a "Stylus Pick" which helps train you to just play the tip of the pick, and not dig too deep, which will slow you down. It a training Tool thast's been around for awhile, used by Berkley School of Music(they heleped develop some of the exercises) and it really does work, at least thus far.

You might want to look into it if you are set on getting really good at AP.