Asteroids are:
Extremely laggy and has a strange long distance rendering that almost appear to be much larger than they are.
Solution:
After a certain distance have the asteroids become low resolution 2D images (the 2D renders used now are extremely disproportionate) and make that distance much shorter, when you are zoomed out to the point of them not being pixel size make them invisible. As well as rings like those of saturn and rings overall, they should at a distance just become simple 2D discs at X number of Km.