How to: Is it really fast?
Yes. See [zsh-bench](https://github.com/romkatv/zsh-bench) or a direct comparison with
[Powerlevel9k](https://asciinema.org/a/NHRjK3BMePw66jtRVY2livHwZ) and
[Spaceship](https://asciinema.org/a/253094).