also, using crystal you have parallel and concurrency to speed up your task. sure it is not as good as other matured languages, but it still does the job.
when doing with large amount of data, and with IO involved, you will see that your JIT or AOT engine for ruby still can not cut it, because in ruby there is so many layers of safety check and failure guard it is really hard to make it faster (number calculation is not everything). with crystal you can manipulate the io stream directly, avoiding a lot of intermediate steps. you can check yourself, they make a full page for it: https://crystal-lang.org/reference/1.22/guides/performance.h...
personally I do not use a single language, I just pick the most suitable language for the job I'm doing, let it be ruby, python, crystal, rust, go or typescript. but surprisingly crystal is the one I use the most everyday.