Sphinx Search

[Simetrical]

I find it hard to believe that anything based on pure MySQL will be able to handle that many posts nearly as well as Sphinx at the moment. MySQL just doesn't have efficient searching right now. You could probably get it to more or less work given enough hardware, if you did stuff like keeping a separate search table and not running updates against it live (to avoid MyISAM's table-wide write locks). But you can't get around the fact that it's just really slow.