moment vs javascript native date

date_conversion_performance.js

 //var today     = moment();

    //1.42 2.53
    //build month grouping hash
    //for (var i=0; i < items.length ; i++) {
    //  var due_date = items[i].due_date;
    //  var grp      = (moment(due_date) < today) ? today.format('MMM YYYY') : moment(due_date).format('MMM YYYY');
    //  if (groupings[grp] == null) {
    //    groupings[grp] = [items[i]];
    //  }else{
    //    groupings[grp].push(items[i]);
    //  }
    //}

    //1.33 2.53
    var today  = new Date();
    var months = ["Jan ", "Feb ", "Mar ", "Apr ", "May ", "Jun ", "Jul ", "Aug ", "Sep ", "Oct ", "Nov ", "Dec "];
    for (var i=0; i < items.length ; i++) {
      var due_date = new Date(items[i].due_date);
      var grp = (due_date < today) ? (months[today.getMonth()] + today.getFullYear() ) : (months[due_date.getMonth()] + due_date.getFullYear());
      if (groupings[grp] == null) {
        groupings[grp] = [items[i]];
      }else {
        groupings[grp].push(items[i]);
      }
    }