I have noticed that when I think about the rhythm of Solfeggio in C minor as a quarter note rhythm, I immediately hit a road block going past Allegro. I get mistakes except when I am lucky if I try to go faster than this with a quarter note rhythm. However, halfing the note that I am thinking of as the base note and thus thinking about it as an eighth note rhythm makes me able to go faster without mistakes. Still not prestissimo but definitely molto allegro. Why is that? Why does simply thinking about the rhythm as being an eighth note rhythm make me able to go consistently faster without mistakes? Is it because eighth note rhythms tend to be in fast pieces instead of slow ones? And would going further to thinking about it as a 16th note rhythm get me to full speed without mistakes since most of the notes, especially in the right hand are 16th notes?