Even after cleaning up the user accounts, the site still seemed a little slow. I spent a while today banning the rest of the ip's that are ddos'ing the site.
Here is a snippet of what one of them looks like:
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:28:40) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:28:40) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:28:43) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:28:44) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:28:45) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:28:46) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:28:47) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:28:48) [GET]
Processing UsersController#index (for 114.84.34.85 at 2013-12-02 02:28:49) [GET]
Processing UsersController#index (for 114.84.34.85 at 2013-12-02 02:28:50) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:28:54) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:28:54) [GET]
Processing UsersController#index (for 114.84.34.85 at 2013-12-02 02:28:54) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:28:55) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:28:55) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:28:58) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:28:58) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:28:58) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:28:59) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:29:00) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:29:01) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:29:02) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:29:04) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:29:04) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:29:07) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:29:07) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:29:08) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:29:08) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:29:12) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:29:13) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:29:22) [GET]
Processing ItemsController#index (for 114.84.34.85 at 2013-12-02 02:29:22) [GET]
Processing RecyclesController#index (for 114.84.34.85 at 2013-12-02 02:29:22) [GET]
Processing CompoundsController#index (for 114.84.34.85 at 2013-12-02 02:29:22) [GET]
You can see they are trying to pull up as many pages per second as they can. So far, this user has over 4000 page views just for today. Once I finally got this one banned, the site was many times more responsive.
I will be actively looking for any more users trying to do the same so don't bother.