`cargo check` is relatively fast compared to `cargo build`, so at least currently, borrow checking is a small task relative to code generation, optimization, an

`cargo check` is relatively fast compared to `cargo build`, so at least currently, borrow checking is a small task relative to code generation, optimization, and linking. There have been many similar changes in the compiler's lifetime, and so far additional type checking work hasn't caused noticeable slowdowns, apart from a few accidentally-quadratic bugs.