I generally say that anything under 500ms is good for commands that aren't crunching data, and even Python CLI tools can come in under that number without too much effort.
The Azure CLI is a good example of this. It's been a year or two since I used it, so maybe it's improved since then, but it used to take a second or two just to run `az --help`, which infuriated me.
If you own a slow Python CLI, look into lazily importing libraries instead of unconditionally importing at the top of each Python file. I've seen that help a lot for slow Python CLIs at $DAYJOB
... also the only tool written in Rust that made it to HN lately that does not scream "I'm written in Rust!" everywhere :)
It also aims to improve on gnu find, not to reimplement it because it's in a non approved language.
It's what the Rust evangelists aren't.
especially in the case of fd, it's way faster than gnu find
sorry if that annoys people, but a rust tool starts with a high trust in my mind that it will fly
ps: to show i'm not in full fanboy mode, i'm often surprised that fzf, brilliant and performant tool, is written in go, but i know it's not rust :)