What they go was this awful compromise, it's not destroyed, C++ promises that it will only finally be destroyed when the scope ends, and always then, so instead some "hollowed out" state is created which is some state (usually unspecified but predictable) in which it is safe to destroy it.
Creating the "hollowed out" new state for the moved-from object so that it can later be destroyed is not zero work, it's usually trivial, but given that we're not gaining any benefit by doing this work it's pure waste.
This constitutes one of several unavoidable performance leaks in modern C++. They're not huge, but they're a problem when you still have people who mistake C++ for a performance language rather than a language like COBOL focused intently on compatibility with piles of archaic legacy code.
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n13...
It does bring up an issue involving how to handle destructive moves in a class hierarchy, and while that's an issue, it's a local issue that would need careful consideration only in a few corner cases as opposed to the move semantics we have today which sprinkle the potential for misuse all over the codebase.
The brute optimisation for Rust is being done by LLVM, just like if you used Clang to compile C++, so your pure number crunching ought to be fine. If anything you may find it's easier to end up correctly expressing the thing you meant with good performance in Rust. If you rely on a C++ library of geometric algorithms, clearly "I can't find an equivalent in Rust" would be a showstopper and so it's worth stopping past crates.io to try a few searches for whatever keywords are in your head
Also, if you know that learning new stuff fogs up your process, you might not want to try to both learn Rust and work on this novel project simultaneously. Some people thrive pairing learning a language with a new project, others hate that and would rather pick, either do something old in a new language, or do something new in an existing one.
If you decide this isn't the right time but keep feeling a twinge, I encourage you to try it for something else, not everybody is going to like Rust, but it's a rare C++ programmer who spends serious time learning Rust and then decides there was nothing they valued from the experience -- particularly if you have no experience in an ML (F# or Ocaml are modern examples)