> in the automatic case ... it's largely correct but often somewhat slower (because it can't elide anything) Not entirely true; in the case of ARC in Swift/Obj

> in the automatic case ... it's largely correct but often somewhat slower (because it can't elide anything) Not entirely true; in the case of ARC in Swift/ObjC a lot of effort was put in to optimizing retains and releases wherever possible. The de facto standard platform for ObjC (Apple's) had a strong set of conventions around memory management already. They were formalized in such a way that some of the defensiveness required in manual retain/release could actually be proved unnecessary in ARC code. (A few semantic changes were made to ObjC as well to support ARC.) Not in all cases, of course, but also not in none.