Noctave
The piece
The sonatina's finale is a Vivace in 3/8 that is felt as one beat per bar. Its theme, two sixteenths dropping onto two repeated eighth-note Cs and then a leap up to a high G, sticks after one hearing and keeps coming back. Clementi gives the left hand the job of engine: broken chords in eighth notes in the first part, repeated intervals later on.
The right hand averages about five notes per second, climbing to six and a half in the sixteenth-note scales that tumble down more than an octave. Pick one fixed fingering for those scales and keep it every time so it becomes automatic. The left hand plays C-E-G in steady eighths: keep them lighter than the tune, without leaning on each eighth, so the bar breathes in one. The trap of a fast 3/8 is rushing the ends of phrases; the staccato eighth followed by rests must fill its whole bar before the theme sets off again. Count "one" per bar, not "one-two-three".