<i>Ruby might just need a better implementation with more time spent on optimization...But also, Lua was always designed with cleanness and simplicity of implementation in mind</i><p>Ease of implementation has a multiplier effect with Open development effort. Not only do you get more of  "more eyeballs," new contributors can ramp up faster. There tends to be a better effort/ fun ratio.<p><i>Even the Ruby lexer is full of weird edge cases.</i><p>Actually, the lexer sets state that changes the operation of the parser and vice versa.