Is it possible to parse something in XML into a perl hash like once, and make any future refference to the hash and not the XML? Like, create a totally new hash file (like .jor) to replace each XML file, keeping the same name, and then if the hash file is missing, look for the XML file and parse that?

I'm a bit new to this, and the only guides I find are for parse-right-now-and-keep-in-the-script sort of situation.

Tie the hash to to a file: http://perldoc.perl.org/functions/tie.html

Personally, I happen to be of the opinion that tie is a feature that is most-often abused, to the serious detriment of the program(s) in question...

To my way of thinking, you should imagine that you are fundamentally dealing with an object, whose solitary purpose in life is to enable you to work with "a Perl 'hash'" that is somehow sourced from "an XML file" (in a fashion that is known only to the object).

So... the basic "method" exposed by this object [class] will be one that, given a key, returns the value corresponding to that key ... exactly as a hash would do. But it has an awareness that "its values come from such-and-such a file," and therefore that if it has not yet loaded that file into memory it should first do so."

Any programming language .. but especially a language like Perl .. challenges you to strike an appropriate balance between "what" and "how." That balance should usually be resolved in favor of "what," but the language (like Perl) might instead try to tilt your judgement (quite erroneously...) in favor of "how." It's a bias that is very hard to shake.