He most likely imported he models directly from Ldraw, he had extremely high poly models
Let me clear things up here, I imported the models from Ldraw into SketchUp to clean them up and lower the faces as possible.
If you remember the plant bush:

You can see how I've lower the amount of faces on my brick.
Admittedly, I slipped up and let some model keep the high-poly parts and that's what caused my bricks to fail.