without knowing the actual system specs (hardware and OS) and how much traffic there is on the server (assuming its not only hosting
www.subsim.com), and not knowing the actual symptoms other than the host is unreachable, does the system shutdown/crash, or just hangs while completing jobs ? or what is it that there is happening behind the curtain?
I'd say that it is not a database issue as I have seen forums with much higher post and member counts that doesnt seem to have these problems that subsim has.
If it was due to excessive load on mysql then moving topics from one forum to another forum using the same mysql isnt going to help one single bit, cause you only moves the load from 1 db to another on the same system, go figure guys
What that might help is to trim the topics and users, for instance prune all topics older than X days or with 0/1 reply, and prune all members with 3 or less posts.
Ban Search Engines by IP address/range, googlebot alone can stall any server for very long periods, especially if the forum it is indexing logs all visitor moves.
Force people to use small signatures, there are still a ton of people using half a page+ to show their signature which is outrageous and abuse of subsims goodwill to allow huge signatures (bytewise not sizewise, come on people think, or Neal will cut down the byte limit)...
Neal PM me server details and the httpd.conf file, the actual filesize of the mysql database(s) and ill take a look at it, also if you have a stats page, i'd like to see the daily bandwidth usage for 3-4 weeks or so