Array.ForEach is about 95% slower than for() in for each for Arrays in JavaScript.
So, don’t use:
var data = []; arr.forEach(function (item) { data.push(item); })
Use:
var data = []; for (var i = 0, len = arr.length; i < len; i++) { data.push(arr[i]); }
See this performance test online: http://jsperf.com/fast-array-foreach