> Reference counting has deterministic timing

Define “deterministic timing”.

- One object going out of scope may mean calling free once, but it also can trigger calling free billions of objects, even for the exact same object

- Even freeing one object can have largely varying running time, e.g. to coalesce free blocks or, because it happens to be the last block in a virtual memory region, to unmap a block of virtual memory, blocking the program potentially for an arbitrary time

- With garbage collection (as with reference counting), lots of the overhead of objects going out of scope can be moved onto a specialized thread.

> you can run a deconstructor without registering objects

Not requiring finalizes does make reference counting easier, yes. The downside is have to store the reference counts somewhere, and keep them up to date (enough)

Yes, but only classes are GC (refcounted as parent comment says, indeed). structs and other elements are not.

You can even use the same ownership model as rust (borrowing et al.) with non copyable types.