It's not theoretical, it's one of the main reasons many large applications abandoned C++, and there's absolutely no reason for it to not exist in Rust. All low-

It's not theoretical, it's one of the main reasons many large applications abandoned C++, and there's absolutely no reason for it to not exist in Rust. All low-level languages suffer from expensive evolution for fundamental reasons - the reliance on an AOT compiler and the lack of movable pointers impose serious performance tradeoffs in large programs. Optimising JITs and moving GCs were invented, in large part, to address this very real problem, familiar to many low-level programmers who have maintained large codebases for a long time. It's also why large runtimes like TCMalloc were invented to assist as much as they can. Most actual Rust programmers haven't maintained a large Rust program for a long time. Now, don't get me wrong - there are many C++ programmers who are fine with it, but many who aren't. What I find annoying is people without much experience in Rust assuming that everyone or almost everyone should like it, even though that's never been true for any language. I'm not saying Rust is bad by any means; in fact, I think it's better than C++ in a few ways. I'm explaining why I don't like it.