Disclaimer: I do not endorse this method over others I see posted, this is just to share an experience :-)

I had a project where I had to "rewrite" a part of the page that had been outputted (this widget at the top MUST change, said management).

my solution was to just save the page off in an array, and going back and massaging the area in question. it was a kludge, but I couldn't redesign this "legacy" app for something that could again change do to some new marketing gadget. In this case in particular, the site saw no performance hit, of course it was only used by a specific customer base on a casual basis, I wasn't facing a million hits a year, let alone a day. Good luck!