The number of posts viewed per page can be set for the whole board, but not by individual members that I can find......maybe Fred can check into it. I know we could do this on the old board, increasing or decreasing the number of posts per page was in our profile.
It is currently set for 40 topics per page, and 50 posts per topic.
What would be the best arrangement? You don't want it too small, because then there are pages and pages and it is hard to follow the discussion. I may be able to give users the option to "not see" avatars and signatures, which would significantly decrease load time.
I like it where it is. Fifty posts per thread page means when a discussion is low key there is not a page to be turned, but if it gets hot then you only have to advance one page per fifty posts. While the page takes a little longer to load for dial up (like me), one does not have to turn the page as often (which also takes a lot of time on dial up).