I angle the pick only for tone, i.e. that scratchy sound.
The fastest rolls are done by choking up on the tip as far as you can,
thumb parallel to the string, pick perpendicular to the string,
and rotating the whole wrist with the forearm as an "axle", as you would if slapping (though the hand posture is different), in a tiny motion as if vibrating.
That's for rolls (one note, many plucks).
For runs the limiter is my left hand as my right can easily outrun it.
practice practice practice.
Does that make sense?
Spector club #243, Rickenbacker #487, Country Bassist #18, Eden #307