I work on quite a large Rust project, and my regular `cargo check` takes around 5 seconds. Of course, I'd be happy if it were instantaneous, but "two deep breaths" worth of turnaround time is hardly a deal-breaker, especially given all the bugs that the compiler prevents for free that I don't need to spend time tracking down.

EDIT: I checked just now and it takes one second to `cargo check` the shallowest crate in our workspace, and six to check the deepest.