Developing speed on a single string requires that we focus precisely upon a few factors:
The width of our pick stroke;
The depth of our pick stroke;
Angle of the pick to the string.
If we can s-l-o-w down our practice, and I mean S - L - O - W down our practice, and isolate a scale fragment, a motif, a scale sequence, etc., and initially on a single string [baby steps before running], then you also should have no problem developing blistering speeds. Speed is NOT everything though, do NOT lose sight of that FACT, do NOT lose sight of the fact that music is not about speed but rather, more about expressing the song that YOU were meant to play. Speed should always be the by-product of a great practice regimen, and not the sole individual goal in playing.
Start at a comfortable pace, a very slow pace because you are going to be doubling whatever tempo you are playing at. I like to do this because it is a lot easier to stay in line with the tempo and not get off beat when you have a slow, steady, identifiable pace underneath you, and not some ridiculous warp speed "tat-tat-tat-tat-tat-tat!!" Trust me, that crap will drive you and everyone around you completely nuts after about 6mins of that. So start at a comfortable pace, play the example twice, and while you are performing the example the first two times, you are actually counting in your head between the beats: "ONE and TWO and" just as if you were counting the eighth notes. The third time around, those silent eighth note(s) that you were counting in your head, you want to perceive as actual quarter notes and thus double everything that you are playing. You will be playing 8 notes per beat instead of 4 the third & fourth time(s) through the example.
You also want to have a very narrow pick width and pick depth. The less area that the pick has to touch is less friction/less area that has to be traversed. You also want to be completely relaxed and not play at your max speed constantly, but gradually, daily, build up the metronome speed from a slow comfortable pace, to a nice jog, to a full sprint; STOP. Get up, go outside, shake your hands out, get a drink, etc., come back, and start the whole process all over again - slow pace, nice jog, full sprint, etc. Do this each day about 3 or 4 times and you will see some incredible speed bursts and speed development.
Personally, I am coming off a bad tendon rip on my left wrist and thus, I haven't had to many posts recently. I am looking great for 2011 and look forward to sharing EVERYTHING that I know with each of you. If you have any personal requests and/or questions, please feel free to contact me at the email below. It is a great honor and privilege to be able to share with others this beautiful language of the soul that we call music. Everyone PLEASE have a Merry Christmas and a SAFE New Year, see you strong in 2011!!! =)
Below is TAB for the complete example. Alternate picking throughout. Quality of notes always before quanity.