XML vs JSON: Incredible performance differences

I admit - I am a real fan of XML and try to use this format whenever it is possible. The reason is simple: It's a clear format and very easy to exchange data with other applications (also with applications not running in a browser).
During the finalization of a project we came across several performance problems with a huge dataset and I tried to move the data interaction to JSON.
The result: The time of parsing a XML with jQuery (loop over the element using each) was up to 100 times higher than doing a simple JSON request (According to the results of the firebug console.timer output). No special treatment, just looping over the records and building an array in javaScript using the default jQuery way.

So, I hope in future times XML parsing will speed up with faster computers (although I think there will be not much gain in the near future because browser XML parsers just use MSXML or Xerces right now).
If you do not have ColdFusion 8 (which offers built-in JSON support), you might take a look at this library.