Any time you see jsperf numbers over about 1e9, that means that the testcase was compeletely optimized out by the JIT (presumably because it has no detectable side-effects so got dead-code eliminated). 1.7e9 iterations per second on typical modern 3Ghz hardware means 2 clock ticks or less per iteration. That's about enough time to increment the loop counter and compare it to the loop limit and nothing else.
Indeed, if you add a completely empty test case, it is only a tiny bit faster than the method version that appears to have such high performance. (jsperf doesn't allow a completely empty test, but you can use // to fool it.)
