The following exercise is an example of a 16th note triple run that is completely diatonic to the key of E minor. This style of 3 note per string fingering is favored by speed pickers like Paul Gilbert and Yngwie Malmsteen. It is important to be very familiar with the 3 note per string fingerings of all of your scales and modes in order to cleanly pull off a line like this. When these fingerings are second nature, there is less to think about. Ultimately, your brain is the barometer for how quickly and cleanly you can play a line like this. I will be posting my G major fingerings and the accompanying modes shortly.
Strict alternate picking should be used. It is important to get comfortable with playing a 3 note per string pattern using a strict down-up picking pattern since each string pattern will begin on the opposite stroke. In time it will feel very comfortable to start a string on an up stroke, but it can be awkward at first. The exercise starts in one position and quickly shifts up to the next position. Make sure your move your whole left hand (including your thumb) to the new position to avoid tension. This is a tough line. Try not to hurt yourself. I'm including an audio clip of my playing this up to tempo. It is possible to really blaze through this type of line when it gets comfortable.