> Note: I'm not saying that Rust would be slow or anything, as you can precisely go as low-level as you wish and circumvent the price of any form of GC.

Rust can also circumvent some of the overhead of Arc<> as it can update the reference count whenever a true "owner" is added or removed, as opposed to just any reference to the object. But yes, you're right that relying on automated reference counting as the default memory management strategy involves some overhead, and tracing GC may be preferable to that. This is a big issue wrt/ Swift.