150-200k is also just the employee’s salary, the actual cost to the company is significantly higher, you need to multiply that by something like 1.5 to get the fully loaded cost, people are expensive!
I haven’t used Ruby much, but anecdotally I once rewrote a Ruby service in Java and was able to reduce the number of servers needed from ~100 to 10. That was a case where it was “frustratingly slow” in practice.