Performance of jQuery.grep vs. Array.filter

In a question it was discussed on how jQuery and native JS would perform against each other.

While of course the vanilla solution performs a lot faster because it does not process the whole array I proposed the usage of Array.filter which I was pretty confident would be at least faster than $.grep.

Surprisingly after adding it to the test I was taught a lesson: Testsuite

Edgecases of course have a different outcome.

Anyone having an idea why $.grep is supposed to be over 3 times faster than the native method Arrray.filter?

Edit: I modified the test to use the filter shim from MDN and the results are pretty interesting:

• Chrome: Even MDN shim is faster than the native method, jQuery way ahead
• Firefox: shim a bit slower than native method, jQuery way ahead

and finally a result like i was hoping it to see in

• Internet Explorer: native method is the fastest, then jQuery, shim is slowest (perhaps this is just the result of IEs rather weak JS-engine...)