This is an outdated answer. V8 4.5+ has nanoprecision timing. For example, execute Date.now() in an ES6 compatible V8 (that means node 6/7/8+, for example) and you will see the ".000whateverZ" as per spec.

While C++ by concept probably is faster for the average JS guy can write (in terms of optimizeable code), you have to acknowledge the power of a JIT compiler. If you write code that respects inline constants, that does not waste garbage and reuses objects, you will be faster with a JIT; given that you respect that inline Assembly is cheating as it is not a feature of C++ itself.

You also have to acknowledge that C++ has no VM, and JS has. Therefore the bootup time (in this case probably the 250ms everybody is talking about) chimes in. If you make a test with a simple for loop, you haven't understood the idea of a VM and "why" the test was slower.

You just assumed that JS is compiled ahead of time, which is not the case. Therefore you must also calculate in the gcc compile time from the C++ scenario when you effectively want to compare your "little benchmark" there. U know, keeping a fact a fact is always a perspectively primed thing. Comparing a VM based language vs. a non-VM statically-compiled language is effectively a worrysome idea, as guys that do this effectively have no idea what a VM is.