I'm not aware of any such scraper. I would first try to subclasss WWW::Mechanize to use some event-based parser or even regular expressions to extract the forms from the response. To save more memory, either do the parsing in the :content_cb callback directly, or store each page to disk and then separately parse the content from there again, either for forms, or for data.

The current trend within WWW::Mechanize skews somewhat towards using HTML::TreeBuilder for building a DOM, but if you have proposals on how an API would look that sacrifices the content for less memory usage, I'm sure that I am interested, and maybe other people are interested as well.

One thing I could imagine would be some kind of event-based HTML::Form parser that sits in the content callback of LWP, so that WWW::Mechanize (or whatever subclass) can extract that data no matter what happens to the content afterwards. But I'm not sure how practical that is, as the response sizes I deal with are far smaller.