Why's it inelegant? The parser has to maintain an internal state as it parses the document in addition to on top of the bare state of a new instance. If there were some huge amount of work to be done in creating that new bare instance then it'd probably be worth antagonizing over, but in this particular case the "savings" in "only" throwing away the document state (were some mechanism in the underlying XML::Parser even available to do this in the first place; since it doesn't it's a moot question :) versus just making a new parser instance is more than likely negligible and not worth fretting over.

Update: Gah, tweaked some phrasing and put a phrase back in that got dropped between brane and fingers.