We have potato?
Potato changes the resolution for rendering everything, with an insanely low 320x180 (I don't know who would actually play like this). It does run smoothly on low-end GPUs but is nowhere near looking like enjoyable.
Adding settings for shadows (which can be very power expensive) and reflections (same goes) would allow for higher quality rendering but better performance on every hardware, including low-end, perhaps drastically.