Quick iteration perhaps isn't the biggest strength of C++ either. Rust does have some friction when it comes to "I'll try this with a dirty impl and if it flies, then I cam make a clean one later". I guess if that friction is worth it will depend on how much faster you get on other things, e.g. refactoring without spending a lot of effort worrying about introducing hard-to-spot bugs like races, or - worse - having to spend valuable time fixing those bugs instead of adding fun to the game.