Ruby was just designed and implemented with all the attention paid to sugary syntax/semantics and very little thought given to how well it could be implemented.

Ruby was just designed and implemented with all the attention paid to sugary syntax/semantics and very little thought given to how well it could be implemented. MRI is a really poor implementation of a (formerly) poorly-specified, highly irregular, unorthogonal language. MRI's garbage collector is abysmal, use Phusion's REE fork to get one that at least doesn't mark every single object on every collection and actually bothers to perform them in normal situations. It didn't do any desugaring at all until 1.9, and YARV only has bytecodes for the most primitive accessors, assignments, stackops, jump/condjump, and returns; with optimizations for -, +, <. <<, and some regexes. Your normal code just gets passed through verbatim. Every once in a while I'll be reading docs or sitting in irb and suddenly scream at the ceiling, spin in my chair, and get the urge to throttle a Japanese person.