I agree that Ruby isn't a good fit for every context, but the reasons for Ruby's speed can and are being addressed, this article is extremely accessible and beautiful:

http://chrisseaton.com/rubytruffle/deoptimizing/

A few critical C extensions are missing (OpenSSL):

https://github.com/graalvm/truffleruby

A recent benchmark (FWIW):

https://pragtob.wordpress.com/2017/01/24/benchmarking-a-go-a...