Tension is the enemy of speed.
At some point you will have to practice fast to play fast. Will it be pretty? No. But it will get better.
Try this. After mastering the piece at a slow tempo, isolate a single phrase or section and start speeding it up, pausing between repetitions to catch your breath.
I've demonstrated this in the video below. The faster I played the D major scale, the lighter my touch became because tension is the enemy of speed.
As Jamey Aebersold pleaded one day to his jazz campers. "Don't practice everything slow!"
revised October 2022
You've got to learn your instrument. Then, you practice, practice, practice. And then, when you finally get up there on the bandstand, forget all that and just wail.
I'm a professional pianist and music educator in West Toronto Ontario. I'm also a devoted percussionist and drum teacher.