I notice you put in your example: <DELIMITER>(.*?)<\/DELIMITER>. Is this because you are working with very large XML files? Or is this simply your way of seperation?

The reason I ask is because I have recently dealt with very large XML files, and found XML::Twig to be very helpful. You can read in smaller chunks of XML data at a time. You can then process it with the same ease as a tree based parser, such as XML::Simple. Once you are done processing that chunk, simply either flush (which prints the chunk) or purge (does not print) the data, freeing the memory.