I haven't used rust in production, but usually you can just use `cargo check` to only run the typecheck. Using `cargo build` is also usually much faster than `cargo build --release`.
Having said that, at least in my toy projects it was not uncommon to have to compile using `--release` to run the tests (since otherwise the tests would take forever).
Maybe you're already aware of that, but if the reason why your tests are slow is not “your code not being optimized” but “your dependencies not being optimized” then Cargo profile override[1] can save your life. You can have one specific dependency (or all of them) being build in release mode even when you're building you own code in debug mode. The first development build is going to be quite slow, but after that, you're going to have the best of both worlds.
[1]: https://doc.rust-lang.org/cargo/reference/profiles.html#over...