I used it in production for a client last yr and i compared that with a go implementation. The concurrency support of crystal on a 40 Core machine beast the socks off golang. Crystal both maxes out all the cores to a high degree, on file io and overall speed of execution. The time taken to do the same task Crystal; beats go by a significant margin while being so easy to write. And go is a easy language to write but Crystal is so much more easy to read because of Ruby syntax inheritance.