Hey There fellow guitar guys! I have been playing for about 5 years or so and have been teaching for 3 of thoes 5... I remember when i first started teaching thinking, why did my guitar teacher recomend me im not fast enough!!! LOL. Well What i did to speed myself up was chromatics with a metronome but another exercise i used was scales broken down and sped up. That pesky little 4th finger always gave me trouble when Id try to play something from: Joe satriani, or Steve Via, or even Van Halen. What I did was I too the Am pentatonic (you can use any scale but for ease i'll give you this one!)

E--8-5-8-5------------------------------------------------------------->
B----------8-5-8-5----------------------------------------------------->
G------------------7-5-7-5--------------------------------------------->
D--------------------------7-5-7-5------------------------------------->
A----------------------------------7-5-7-5-5-3-5-3-------------------->
E---------------------------------------------------5-3-5-3-5~~~~--->

It's nothing special but it sped up my 3rd and 4th finger (the wakest). To start on this you can try alternating your picking when you get better at it you can hammer on and pull off all the notes picking only on the first note you play. If your gain is high enough you can just fly though it. Unlike practicing chromaitcs this lick you can actually use for soloing! it has a practical use.. but even though you can do it with "distortion" its always important to try it on the dood'old accoustic! a clean tone dosnt cover up mistakes and is a real test of your guitar technique!!! Remember start slow and then speed up as you go!!

Enjoy!
Ken