Ruby is great in terms of allowing people to experiment with different algorithms pretty quickly. It's easy getting the code written and tested because the code tends to be so succinct, the standard library already includes a lot of shortcuts, it's synchronous, there's a lot of metaprogramming features readily available and the interpretation allows for quicker testing when you can get the basic syntax right after some experience without requiring the help of an IDE as most Ruby code is written in text editors.

Languages that demand IDEs tend to be more complicated in many ways. They can be faster, but also might demand more code obfuscation through more code that need to be written like types and longer names and importing of libraries and so on. My pet peeve is that I absolutely love Ruby, but it indeed is not meant for ultimate performance. On the other hand, languages like Dart might allow for some compromise if you can get stuff done with less power at your hands like less metaprogramming and fewer shortcuts... Except that Dart is trying to tackle asynchronous programming with the standard libraries which is itself quite complicated (Future what?)

Go and Dart are not themselves too tuned for performance yet, even though they tend to be very quick when compared to Ruby. They tend to solve different problems though.

Ruby has a couple of architects, Matz and SASADA for the VM. Go has a few. Dart has many, with some tending to the standard libraries.

Programming is unfortunately way too complicated. In my opinion, languages like Ruby are wonderful when you don't have a need to hide the source-code. On the other hand, languages like Go and Dart might be good when you do have a need to hide the source-code when deployment time comes.