If you are really good at finger picking, why mess with a good thing??? Go with what works for you. And like someone previously said, Jeff Beck is lightning fast without a pick. But if you are determined to work with a pick I have one word that you need to mentally picture in your mind every time you pick up the guitar pick:

RELAX !!!

Not relaxing when you pick is the single biggest reason guitarists have trouble playing with speed with their picking hand. Watch guys like Steve Vai, Joe Satriani, etc. Watch their picking hands. Observe:

What parts of their body are they moving when they are picking? Are they moving their shoulders, elbows, wrists, or are they moving a combination of those body parts?

Are they using alternating down, up, down, up strokes or are they using one of the many economy picking techniques that are out there?

Are their hands free floating or are their picking hands resting against the bridge when they play?

There are a couple of video cassettes out there which demonstrate some of the various economy picking techniques. Jimmy Bruno and Frankie Gambale are two names that come to mind who have put out videos on the subject.