Cool. This leverages JIT compilers ability to generate fast code (at the expense of language expressiveness, for it obviously works well with static style code

Cool. This leverages JIT compilers ability to generate fast code (at the expense of language expressiveness, for it obviously works well with static style code only). I wonder what a "JavaScript JIT optimized C dialect" would be? Ie. what are the C mechanisms that are too expensive with today's JIT engines?