My most recent example is a prime sieve I wrote in Racket which was at least 10% faster than the Python implementation (can’t remember the exact number right now) I modeled it after, and then another 10% faster than that when I converted it to typed-racket[1]

For interactive development it’s true Racket isn’t as heavy into top level development as other lisps, but I often run my code and then play around with modifications to it in the repo afterwards using racket-mode in Emacs.

[1] https://github.com/diego-crespo/Primes/blob/drag-race/PrimeR...

Racket is not so interactive: https://gist.github.com/vindarel/c1ef5e043773921e3b11d8f4fe1...