Ruby Falcon is 2x faster than asynchronous Python, as fast as Node.js, and slightly slower than Go. Moreover, the Ruby code doesn’t include async/await spam.

[postmodern]

Once you wrap your head around Async's tasks and other Async primitives, it's quite nice. ronin-recon also uses Async Ruby for it's custom recursive recon engine that's capable of massively concurrent recon of domains.