Javascript benmark and experiences

javascript.js

var c = $("#comments .comment"); // 4,649 ms
// jQuery 2.0
var c = $(".comment"); // 3,437 ms
// native querySelectorAll
var c = document.querySelectorAll("#comments .comment"); // 1,362 ms
// native querySelectorAll
var c = document.querySelectorAll(".comment"); // 1,168 ms
// native getElementById / getElementsByClassName
var n = document.getElementById("comments");
var c = n.getElementsByClassName("comment"); //107 ms
// native getElementsByClassName
var c = document.getElementsByClassName("comment"); //75 ms