> also ref.counting overhead per item (AFAIK even when reading stuff). That's the beauty of the borrow checker: no, there's no reference counting overhead when

> also ref.counting overhead per item (AFAIK even when reading stuff). That's the beauty of the borrow checker: no, there's no reference counting overhead when reading stuff. The borrow checker guarantees that the reference you used to access the value won't go away until you're done with it, so it doesn't have to increment the reference counter.