I have it running OK now.
Really basic (OK, stupid

) question. What do I need to turn OFF in vB to keep it from using its own internal search engine? IOW, aren't the built-in vBulletin search index tables going to be populated with the newest posts as they are made? From the way I see it, Sphinx bypasses the whole vB system, so vB shouldn't need to store any of the search terms anymore, unless another search process uses it. I've already dropped the fulltext indexes and changed the search type from fulltext back to vB internal, and am switching selected tables over to InnoDB to clear up the load issues we're having.