Tense wrist in the feux follets rapid double note passages

First, I wouldn’t try to play it at faster speeds at all. As soon as the wrist tenses up, it will be counterproductive. Instead I’d practice it only at a tempo you can comfortably control with a wrist that’s free of unnecessary tension.

Second, it’s a really good idea to practice this passage as softly as possible. This will also help keep your wrist free.

It’s not for nothing that Horowitz called “Feux follets” the hardest piece he ever played. You can do it with patience and never forcing the sound. Best of luck!