Best practice for optimizing processing of big XMLs?

Question

All,
What is the best practice when dealing with large XML files ... (say couple of MBs).
Instead of having to read the file from the file system everytime a static method is run, what would be the best way in which the program reads the file once and then keeps it in memory. So the next time it would not have to read and parse it all over again?
Currently my code just read the file in the static method like ...
public static String doOperation(String path,...) throws Exception
try{           
String masterFile = path+"configfile.xml";
Document theFile = (Document)getDocument(masterFile);
Element root = theFile.getDocumentElement();
NodeList nl = root.getChildNodes();
// ... operations on file
Optimization tips and tricks most appreciated :-)
Thanks,
David

Answer 1

The best practice for multi-megabyte XML files is not to have them at all.
However if you must, presumably you don't need all of the information in your XML, repeatedly. Or do you? If you need a little bit of it here, then another little bit of it there, then yet another little bit of it later, then you shouldn't have stored your data in one big XML.
Sorry if that sounds unhelpful, but I'm having trouble imagining a scenario when you need all the data in an XML document repeatedly. Perhaps you could expand on your design?
PC²