I display the GPX track using standard OpenLayers functions on map material of the OSM project. For example, check out this this post on my friends blog:

http://www.walking-away.de/wanderung-maligne-canyon-jasper-np-alberta-kanada/

There you can see a map which display the GPX track.
Additionaly i wrote some PHP code to extract more information from the track to display the elevation profile below the map using the Google Chart API.
What my problem here is that it takes too much time for PHP to get all the information out of the linked GPX track. I already improved my parser but it didnt work out.

Since OpenLayers already loads the track one time, it would be great to use the already loaded track directly within JavaScript to get the information i need (like distance, elevation and so on…). When OpenLayers loads the GPX track, the information has to be there anyways. The only question is: Are there ways of getting all the information i need out of the loaded GPX file.

I hope this helps.