This is one of the best speed exercises where you can improve your alternate picking speed, and technique and get faster by John Petrucci. I usually teach this unison to my students and I observe significant improvement in their playing.
This solo is written by John Petrucci in quintuplets so first try to nail quintuplets by counting out loud and tapping your foot.
Please use your wrist and try to increase your speed gradually.
Cheers
Ozz