gistfile1.js

var obj = {},
  needed = 1024*1024;

for(i = 0; i < needed; i++) {
	obj[i] = "avx";
}

function forLoopTest() {
	var start = process.hrtime();

	setTimeout(function() {
		var end = process.hrtime(start);
		console.log("for: Blocked time: ", end[1] / 1e9, " ms");
		
		process.nextTick(function() {
			foreachLoopTest();
		});
	}, 1000);

	setInterval(function() {
		for(var key in obj) {
			if(obj.hasOwnProperty(key)) {
				//console.log(key);
			}
		}
	}, 5);
}

function foreachLoopTest() {
	var start = process.hrtime();

	setTimeout(function() {
		var end = process.hrtime(start);
		console.log("foreach: Blocked time: ", end[1] / 1e9, " ms");
		
		process.nextTick(function() {
			process.exit(0);
		});
	}, 1000);
	
	setInterval(function() {
		Object.keys(obj).forEach(function(value) {
		
		});
	}, 5);
}

forLoopTest();