A lot of performance-increasing features/restrictions implemented in Crankshaft are not yet implemented in TurboFan. I wouldn’t expect faster code before a first completed implementation. I’m really curios how much the speed gain will ultimately be. And SoundScript (typed JS) looks promising as well!

I experienced in a few quick tests that using TurboFan was literally starting the laptop fan and executing my test code took longer. AFAIK it’s still rather experimental, but luckily it only gets activated by explicit user control. (I think Chrome already turns it on for *some* code by default, but only when relatively sure that the compiled code will run fast).
Seems it has some way to go, but it looks very promising. Same for strong mode: looks very promising, too, as it allows compilers to ignore certain JS features that would render some optimizations impossible.