I just installed caching on the server and need to see how it's affecting everyone. This wasn't easy for me, as I had to get into the linux root in order to get it installed. Supposedly, it will store more information about the forum into the memory where our fast processor can snag it, rather than it needing to be loaded from a drive. I'm not going to bias this at all by giving my opinion on the speed until some others have chimed in. Only bother telling me if you notice a significant difference either way.
Theoretically, this will free up the disk access times a bit for the guide by shifting burdens to different resources.