I have noticed that even after months of practicing C.P.E. Bach's Solfeggio in C minor, I still can't get past Molto Allegro. I have tried thinking of it as an eighth note rhythm and that actually helped me get past the Allegro roadblock but I immediately hit another one after getting up to Molto Allegro.
And I am still not near full speed because full speed is prestissimo.
But this has prevented me from practicing a lot of Chopin's pieces including his minute waltz. I am scared I will hit the same roadblock with anything at presto or prestissimo as the one I hit with Solfeggio in C minor, no matter how much time I perfect it at Allegro. Even the Toccata and Fugue in D minor sounds like it would trip me up because a section of the toccata is at prestissimo.
I am advanced enough to practice the Liszt transcription of Beethoven's 5th Symphony. So Presto should be a breeze but no, I can only seem to reach it with my own compositions. Trilling at Allegro for multiple measures is way easier for me than Presto even though the note speed in the trill and in a Presto piece is the same.
So why do I have this roadblock at Presto(like always getting mistakes except for a few lucky times if I try) and how can I eliminate this roadblock if lots of practice at Allegro and eighth note rhythms aren't going to do it?