Speed ups? Where are you seeing speed ups? I'm on a Macbook (last gen) and have been using High Sierra for the last month or so. Aside from my changed desktop background, I haven't actually spotted (any / many?) changes.
General animation things because of Metal 2. APFS is awesome when copy pasting (instant), Safari's faster, and general performance increase (subjective of course).
Yup, which is pretty neat. Before you'd have to wait for the little Finder window to show up, calculate time remaining and then do the job. Now it's instant when copy-pasting files around :)