I have tried that, and i can pick pretty fast. if i don't play any notes while doing it, it seems to be going fine, if i then add notes i become tense very fast.
Also i think it's the way i pick that something is wrong with. If i don't play any notes and do fast alternate picking. i don't become very tense and the picking seems different. Less movement and better handplacement. If i add my left hand and play something, my picking changes into a type of pick attack where i almost pick vertically and jumping onto the different strings with less effeciency. Check out the video, i think it's noticeable.