March05, I think the reason I can play the first etude at this speed comfortably is that after each set of four notes my thumb is already in place to to start the next four notes. The way I originally practiced it was to play all four notes and then move my thumb as fast as i could to the next octave up. I quickly found out this was not the way to do it. Rather, in the first grouping of notes (C,G,C,E) when my fourth finger plays that third note in the group (C) my thumb has already shifted a lot and is rather close to that next C already. I practiced this etude for a while doing this: Just playing the first three notes of each arpeggio (in the first one C,G,C) with the fingering you would use, so in this case 1,2,4. And then jump the octave and do it. It is very similar to op. 25 no. 12, except that you are using different fingerings. By doing this you will cause your thumb to travel right after it has played its note. The only real trouble i had in this etude were the A major arpeggio and the arpeggio that had Bb, F, Ab, and D. All of the others came pretty naturally.