Thank you for your tips, guys. I will start reading about the LOD system right now, and with respect to model-levels, I think it's too late to go back...unless there's a way to completely convert my block-level into the latter. And even then, as ulililia pointed out, model-levels are less diverse as respects to lighting.

P.S. Very nice model-level by ulililia, but again, the lighting is honestly very limited.