Cache DOM fragments

Always cache DOM fragments rather than waste CPU time if you were to make jQuery walk the DOM each time

HTML

<select id="my_select"/>

JavaScript

//an array to use for demonstration
var arr = ["one", "two", "three", "four", "five"];

var $frag = $();
$.each(arr, function () {
    $frag = $frag.add($("<option/>").val(this).text(this));
});
$("#my_select").append($frag);