Graal isn't a game that has polygons with texturing, so decreasing the quality of the graphics would do nothing. In fact, it'd probably increase the file size of images since more blurriness = more colors to store = higher file size.

The drawing distance on devices is determined on the zoom you've set. Try playing on PC with the highest window setting compared to having it on the smallest. The smaller size will be way faster so that's already in place.

Lights on Era are just images, except not as opaque, so it renders the same as anything else and doesn't make a difference compared to loading another image.

The entities that make the biggest difference are the players, particles, bullets and their collisions, and the gang system, and none of those can really be changed, except for maybe the gang system which would require a complete overhaul.