That’s just not true. Rust has a wonderful type system and it can encode mutability, which is a must for anything performance oriented. That is a benefit that FP misses out on. You can still analyze Rust programs with a great deal of assurances. The fact that it’s procedural seems to not matter much at all.
An example of a language that allows mutability and has a research-level type system is Flix.
> [...] which is a must for anything performance oriented.
But that's also not really true.
Using functional data structures it is possible to write highly performant software. Check out for example "CppCon 2017: Juan Pedro Bolivar Puente - Postmodern immutable data structures"[1], an impressive talk, in which someone shows their developed editor that can edit huge text files without lag faster than any mainstream editor today. This is enabled by functional data structures. Usage of functional data structures throughout a project also ensures, that parts can be trivially parallelized, which is not true for traditional algorithms, and therefore can easily scale with number of CPUs available. For more on that subject, you might want to watch a few Joe Armstrong talks.
Rust achieves type safety by introducing more language concepts like ownership, borrowing, and lifetimes, to formalize, who has access when and how. It also creates things as immutable by default, unless you make use of `mut`. Unfortunately, Rust's philosophy is shared memory and making shared memory access safe, rather than message passing, which is at odds with FP.
