One thing I forgot to mention, it's something I learnt from the Michael Angelo Battio instructional dvd "Speed Kills".

Get your plectrum and play one note as fast as you can with a perfectly even rhythm (it doesnt matter how fast it is, the most importnat thing is that it is comfortable for your hand and that you can play it for a long time without losing tempo). Now look at how you are holding your plectrum and how your hand rests on the strings. Make the necessary adjustments to ensure that you can play the same speed and keep unused strings muffled. This is your "maximum picking ability" (for now).

Everything you play from now on should be based on the exact technique you personally use to hit your top speed. So even if you are playing the 123 exercise at one note every 2 seconds your picking hand is moving in exactly the same way as if you were playing 16 notes per second. A lot of players starting out lose clarity when they up the speed of their picking becasue they change their technique. Stick with one hand position from the start, it will improve your ability by 200%.

Picking speed will increase with practise, getting the left hand in sync is what the 123/1234 exercise is all about.
Best of luck