Play it slowly until it’s right. Speed shows up later, uninvited.

Speed is a result, not a method. Playing something fast before it is accurate trains the mistakes in at tempo, and then you have two problems instead of one. Slow repetition feels like it is going nowhere while it is actually building the thing that speed will later run on. That is why the patient version arrives sooner.

Set whatever you are working on slower than seems necessary and hold it there until it is clean three times running. Resist the urge to test the fast version. Let the speed turn up on its own.