[nindalf]

I remember reading that it does, but because the LLVM IR generated by rustc is verbose. If less IR was generated, LLVM would have less work to do.

[masklinn]

I think that's one of the eventual purposes of MIR (by both optimising Rust upstream from the LLVM IR generation and having a much simpler language to generate IR for), but I don't know if there's been work towards that yet.

[epage]

I thought it was two factors (1) unoptimized IR and (2) large translation units (crate rather than file).