There are many special techniques to deal with playing fast scales:
1.Play the scale in chords.
2.Always increase speed by increasing the speed hands separate. It is the HS speed that will limit your HT speed.
3.Use a thumb over movement.
4.Decrease movement range. And make movement as efficient and economical as possible.
5.Do not practice slow (practicing slow is not for speed is for other purposes), although it is all right to practice in slow motion.
6.Do not play thumb under.
7.Do not start the movement from the fingers.
8.Do not use exaggerated inefficient movements.
9.Do not use a different finger for right and left hand: the left hand will slow you down.
10.Do not try to increase speed by practicing hands together.
11.Do not practice mechanically.