Autotune monitors your framerate over an extended period and gradually adjusts graphics settings until a target framerate is achieved.
The purpose of this addon is not only to select suitable graphics settings, but to addapt dymaically to performance changes cause by variance in zones and background activity on your box. For example, when I have too account on at the same time the tuner will lower the graphics settings on the background account while providing a higher level on the account I am using. Autotune remember the tuning level per character, and reapplies this at login.
The addon also includes a Medic, feature, which will lower setting temporarily in reponse to a lag spike and restore them to the previous level once your framerates return to normal.
While I believe that the defaults will be good for most equipment, I have a mid range box, and cannot of cause be certain that my choices are perfect for a low spec or high spec box. So, if you wish you can control the target framerate, the starting level, the frequency of tuning, and which options get tuned. I have included Character and Texture in the tuning, but since these require a relogon to take effect, I suggest that you untick these once you have found a suitable level.