IIRC it's a combination of technical debt from earlier in Rust's life (it's easier to generate naive LLVM IR and let LLVM's optimizer do the heavy lifting of chewing through that) and how Rust implements generics via monomorphization

> and if that can't be reduced somehow.

I believe the technical debt bit can be (and is being!) reduced by implementing optimizations and better IR generation in rustc itself. As for the monomorphization strategy, I thought I remembered reading something about how Rust technically allows for generics to be implemented via non-monomorphization strategies like type erasure/dynamic dispatch, but I can't seem to find that post/article/whatever it was now so I'm not sure I'm not making it up. That being said, there are patterns to reduce the amount of code generated (e.g., generic facade that forwards to a non-generic implementation), but those need to be manually implemented at the moment and I don't think there's significant work towards automating that at the moment.