I'm not sure the Rust JIT feature looks far enough along/well maintained enough to actually work with a typical rust program and when it does it sounds like it's probably slower than AOT anyways https://github.com/rust-lang/rustc_codegen_cranelift/blob/ma...

I think it also only does the backend? I.e. you still need rustc to compiler to do everything but the codegen whereas this seems to be the whole compiler portion of the toolchain "Relax isn't a wrapper around rustc or a plugin for LLVM: it replaces both, and the parts of Cargo and the linker in between."