There are very few questions for which DPL is the appropriate answer. This is not such a question.
One of the many concerns related to the DPL extension is performance. This is better done as a QueryPage, like the core Special:Unused* pages. I've written such an extension, which adds a Special:UnusedRedirects page. Obviously it could use a bit more testing, but based on some quick tests on my local dev wiki, it seems to be working as intended.
I've filed a request for a new git repo for publishing the source code; I'm not sure how to properly add it as a git submodule for the Brickimedia/extensions repository, but we can deploy it to production without that and have someone more git-savvy clean it up at a later date.