Meta theme environment scene example?

I would be happy to take a sneaky look at the home scenes from Meta to understand how the hell they reach 72 fps with that level of detail 🙂

I can't get more than 40fps on a yet optimized simple scene of my own, whatever I use (baked lightmap only, mixed lights, no shadows, 1 merged mesh only with only a 2048 px packed tex without normals neither height... Well I just get 72 fps with an empty scene, that's freaking me.