I have cache disabled like mentioned above (I did that last week). I have everything disabled that has anything to do with cache. I'm not concerned about performance because it's such a small forum with few posts.
I don't have any spam posts at all. How could spammers be affecting my cache, which I have to clear once daily?
Once I clear the cache, my forum is using 93 MB's. Within 1 day, it will jump up to 200 MB's of disk usage. I clear the cache, and it goes back down.