The borrow checker is only one reason for the slow compile times. Cargo provides a separate `check` command to only do code & typechecking and that can be much faster than full compilation. LLVM and the way rustc interacts with it also plays a role.

In my experience when compilation takes longer the actual delays are in the last steps, long after the compiler is done checking and printing warnings.

On an unrelated note, I also noticed a large amount of static string literals in the code can slow down compilation to a surprising degree.