From my personal experience this is the hardest piece in book 2 actually but the benefits in playing this speed on 100% are spectacular, because it increases left dexterity and agility to help for fast passages so my advice for people who struggling in this kind of tempo Is be extra patient developing the clarity of each passage and learn to manage your energy on each passage. it is important that you wont get tensed up during the difficult runs. So start of with just minimal energy then when the difficult runs arrive thats where you use more energy and concentration on. Practice hard but not too hard Hope it helps...