In my experience most Ruby apps (Rails in particular) develop this idea that Ruby is the bottleneck when in reality most of the time it's something else entirely (mostly DB or network IO). Of course you found compiled languages faster! that's by definition. You also tried Ruby on CPU sensitive code bases ("Advent of Code or Project Euler solutions"), that's textbook "ruby is slower than C". Rails pays dividends in the web and in large code bases with many engineers.