[Simon]

Another option could be to move older stories to an archive (move them to a separate database table) - and use a very simple text only viewing for old stories. Similar to what forums like vbulletin do with their archive viewing.

That way all stories can still be viewed in a "pligg_archived" table, and the pligg_links table will never become so big as to affect performance. You could also cache archived pages once they had been viewed once, since they will never really change.