The level size doesn't matter. Even if you went clear out to 100,000 quants diameter, any 2x2x2 block will, to some extent, cause problems. With models, you don't have this limitation (and they render up to 100 times faster allowing for 100 times the detail). A tiny level is anything less than 4096 quants in diameter (extending 2048 in each direction from the origin). If using prefabs, make sure you don't scale them. If neither is the case, then what version and edition do you have? In WED, go to help > about. Two examples are 6.20.2 Pro and 6.40.5 Extra.