Sometimes I do similar arps, but with a wider voicing. Let's say, I play a c-minor-arp from high to low. In fact, I'm playing most of the time chords with (added) 9th, so the notes, I'm using are C, D, Eb and G (no 7th in this example). The numbers are the fingers of the right hand, I play the note with:
C5, G3, Eb2, C1, [handmove] G5, D3, C2, G1, [handmove] C5 etc.
C1, Eb2, G3, C5, [handmove] G1, C2, D3, G5, [handmove] C1 etc.
Speed comes with the time... this can be played with major chords too. If you want to bring the 7th in, you could play a c-minor as the first chord and a g-minor as the second, as the g-minor contains the 5th, 7th and 9th of the c-minor-chord.