You can make it pretty darn robust! OCaml compiles very quickly and has a good type system. Rust is slow due to LLVM, macros, and the compilation unit being the entire crate. None of these are requirements for a good type system
Zig's new compiler is a nice example of how you can do all sorts of inherently slow things at compile time and still have a lightning fast iteration time for developers if you design your toolchain for incremental compilation instead of making the compilation unit be the entire module the way Rust did.