I have noticed that the posts pages have been growing. I think you should, that is if you want to, keep all posts so people can go back and look at those just to see what topics were being discussed and all, but I would suggest archiving them by month. For Example:
It is June, so keep all May and June posts, on the "fresh/current" board, but put a URL on the bottem that says "April" where people can access the posts from April. And then in July Archive May, otherwise it seems there will be sooo many posts, or pages of posts, it might overwhelm some people. I don't know, just a thought, keep it in mind