Holding a pick shown below in the first pic is great for strumming chords and basic picking, but not for playing speed! Most speed players like Paul Gilbert, Yngwie Malmsteen, will tell you that when speed picking they hold there hand at an angle and pick loosely almost on the tip of their fingers.
Another reason why guitarist do this is to achieve the harmonic qweal just by pinching the end of the pick. This will case the thumb or finger nail to touch the string producing a artificial harmonic. The 2nd pic below is the correct way to hold your hand and pick for speed. Your thumb and first finger should produce a complete O shape. When you see O then you'll know your doing it right.