According to amachang, the code below accerelates JavaScript on IE 5 folds.http://d.hatena.ne.jp/amachang/20071010/1192012056 (Japanese) /*@cc_on _d=document;eval('var document=_d')@*/ He claims thatvar doc = document; doc; // this one is faster document; // than this And the trick above does just that. This is more of a bad know-how than a hack but it is worth mentioning. FYI I am a Firefox