It&#x27;s not a bug, and the answer is provided in the link:<p><i>&quot;Faster execution time. You may have noticed that in the new compiler pipeline, optimization appears twice. That’s no accident: previously, the compiler relied solely on LLVM to perform optimizations, but with MIR, we can do some Rust-specific optimizations before ever hitting LLVM – or, for that matter, before monomorphizing code. Rust’s rich type system should provide fertile ground for going beyond LLVM’s optimizations.&quot;</i>