> LLM code is abysmal if you look at the details

This is, unfortunately, false.

Yes, if you one-shot some code with an LLM, it can be terrible. But if you let it profile and optimize it, there is no obvious limit. LLMs have more patience to investigate performance issues and fix them than humans.

Again, I wish this wasn't so, but I see it in my job daily. There is code in my projects that is vastly faster because of LLM optimizations. Not only can they find more in less time, but they find things I and my co-workers would not have thought of.