ok. Study the passage with lightness and speed, taking care to watch for the rapid movement of the hand position ...Without "thumb underneath" but "thumb at the side". Last thing: to not fail the passage, always think ahead about where "you need to arrive", mentally anticipate the final note (the C in the first long arpeggio and the G in the second long arpeggio)
talking about "lightness".. besides keeping the wrist raised (this is what I remember from past studies), is there any other precaution that I am currently missing?
What exercises could I do to develop/consolidate "lightness"?
None. Lightness in the sense that the weight of the arm and shoulder must not prevent the rapid shifting of hand positions. Think of it as if they were repeating chords: do mi la do mi la do do. Practice moving rapidly but without stiffness between these positions, perhaps playing only the thumb as a reference.