Efficient looping in Javascript

Hi Guys,
I read a great article that talk about the Efficient looping in Javascript.
If you are a big fan of Javascript Libraries like Prototype and Mootools, this article will show you the performance problems of some of these Libraries Iterating like:
Array.each()
Native For-Loop
Native For-In-Loop
Prototype Each-Loop

etc.....

Efficient looping in Javascript