I think I just inadvertently proved the point that a lot of replies to the original commenter were making. If you just say "I benchmarked this and X was way slower than Y" without posting code or other details, then it's likely that you're doing something wrong, particularly when you aren't familiar with X or Y.

The original poster said:

> To me that means performant Lisp is non trivial (meaning you need deep understanding to achieve it). If you show a slow but easier to understand example, it’s because fast examples are way harder to understand.

And

> What I was trying to see is, can I do something useful with this? Or do I need to invest a good amount of time (something I don’t really have now) before being productive.

I could have equally said that my example demonstrates that "To me that means that performant Rust is non trivial" or that I would "need to invest a good amount of time ... before being productive"

Both of which are clearly not true. Posting my code let other people find the extremely trivial change to fix the huge performance difference.