Ruby has its jit disabled by default as far as I can tell^1 . Lua exists in both jit compiled and interpreted forms. Python definitely is interpreted unless you

Ruby has its jit disabled by default as far as I can tell^1 . Lua exists in both jit compiled and interpreted forms. Python definitely is interpreted unless you run it through pypy. JavaScript is basically the only language in that lineup that enables just in time compilation with most of the "default" runtimes. ^1 Most likely because it generates C code and has to call an external C compiler to get things done.