Add table to speed up forum list / topic queries

The queries in forum_get_forums and forum_get_topics are notoriously slow and not really fixable. There are core issues with all sorts of ideas for fixing the problem but nothing committed. I discussed on IRC the possibility of fixing it in AF:

[20:59] <merlinofchaos> The only way I can think to do it is to basicaly create your own materialized view, which is to say to create a forum_topics table with all the appropriate data.
[20:59] <merlinofchaos> nid, status, last comment time and anything else that might get sorted on.
[20:59] <merlinofchaos> and keep it up to date during hook_nodeapi
[21:00] <merlinofchaos> oh and tid

So that's a possibility. Unless someone tosses a well tested patch in my lap, this is unlikely to go any further until AF 3.x and possibly D7. I just wanted to record the conversation and put it out there as an option.

Michelle