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.
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.