I'm not a coder but theoretically this may be possible.
the app would only need to strip the forum of most of it's coding to only leave a simplified version of it.
there's a website called skweezer.com that I use to render pages that load faster on phones.
the website strips the page of most of it's code and formating.
skweezers an extreme however.
I guess what I'm saying is the app should be a browser:
a browser that doesn't try to render full pages, instead it'll try to render the pages so that they'll be easier to read on the phone and as a result the pages would be rendered faster.
it'll remove fancy formating and resize tables to fit to the screen. it'll also remove large images (maybe replacing them with thumbnails would be best