This auto-business lookup and those popups have been making my workflow miserable, too, especially when I’m just entering local customer sales. There’s no real off switch for the Business Feed in QBO right now. I’ve looked everywhere and keep running into the same brick wall.
Best workaround I’ve got: when adding a new customer, I just fill in the Display Name and leave everything else blank until after I save. It skips a lot of the auto-fill junk. Still annoying, but it gets me past the freezing and double-name issue most days.