Underscore.js foreach vs native for loop speed test

foreach vs for loop

// Build 100000 alphabet dictionaries
var dict = {};
for (var i = 0; i < 100000; i++) {
    dict[i] = {};
    for (var c = 65; c < 65+26; c++) {
        dict[i][String.fromCharCode(c)] = c;
    }
}

// Loop through parent and child dictionaries in native JS
var t1 = new Date().getTime();
var length = Object.keys(dict).length;
for (var i = 0; i < length; i++) {
    var subLength = Object.keys(dict[i]).length;
    for (var l = 0; l < subLength; l++) {
    }
}
var t2 = new Date().getTime();
console.log("For loop: " + (t2 - t1)/1000 + "s");


// Underscore
var t3 = new Date().getTime();
_.each(dict, function(v, k, l) {
    _.each(v, function(v2, k2, l2) {
    });
});
var t4 = new Date().getTime();
console.log("Underscore.js foreach: " + (t4 - t3)/1000 + "s");

2017-04-05 Chrome Version 56.0.2924.87 (64-bit):

For Loop: 0.143s
Underscore.js foreach: 0.171s