I think this is a bit of an exaggeration and over-hyped by people who don't like the language or use it frequently. While not as fast as a compiler explicitly designed for fast compile times (Go) or a compiler which leaves most of the work to the JIT at runtime (Java), Rust's compiler isn't that bad for compilation times.
Whenever I develop in Rust I'll have
cargo watch running on another terminal, continually recompiling and running my tests whenever I make changes. Because of incremental compilation and
cargo check I'll often see type errors pop up within 3 or 4 seconds of hitting save.
I was even seeing this when hacking on the rust-analyzer codebase (I made the inline-function assist), which is about 170k lines of Rust!
As long as your CI uses caching properly, I've found I can get my pipeline times down to 5-10 minutes. That's usually good enough for my purposes because it gives me a chance to add extra information to the PR or start on the next issue and hit "merge' when GitLab's "your build has passed" notification pops up.