Re: All setting use cache
There is no actual page cache in bbPress. The cache setting you see is meant for the *object* cache which is meant to store things like the user data and the forum data in shared memory (memcache) for multi-server environments. It could be used on a single server but the performance increase might be trivial compared to a good cache on the mysql db since the core “engine” still has to load.
The only real cache that could speed up bbPress is a page cache like wp-super-cache which bypasses the WP engine entirely. It would have to be ported eventually. But that only helps for users that are not logged in and the idea of a forum is for people to be logged in and interacting.
Currently I cache parts of pages like the front-page tag cloud on my own installs but I have not released the plugin for that.
Speaking of tags, while they may have fixed the forum query count in the trunk, I now see another problem where apparently bbPress 1.0 is making a query for EACH tag in the tag cloud. Once they fix that, queries should go down again.