We've had a number of issues this past week. Chinese spammers posting thousands of threads, and we've also had a tremendous amount of traffic from botnets.
This morning I made a move to migrate us to a new frontend protection service called CloudFlare which provides an extra layer of protection for the site, and should help a lot with the site slowdowns that are caused by the botnets. It will not protect against spammers. For that, we will continue to just be proactive in shutting them down when they come. Soon I'll also make it so new "members" can only start a few threads per day so they don't post thousands at a time.