At the bottom right there is an "archive" link that'll take you to a very simplified view of the forum. Every extant thread, AFAICT, is there, and when you open the one you are looking for, it holds a lot more posts per page than usual - not the full thread, but more than 30. It also removes a lot of the bbcode, so things like spoilers aren't too much of an issue. It does also break quotes, though, so it's not perfect.
ETA: Oh, and see this post on how to find the archive of the thread you are looking for
Grey wolf