What's more performance-friendly? 2D Physics or Animated FBX?

Hi,

I want to have falling rocks (simple lowpoly meshes with 2D Colliders attached) in my mobile game. Can anyone please suggest me what's more performance-friendly having them animated in 3d package and then importing them as animated FBXs in game scene, or using real 2D physics inside of Unity and having them falling down and reacting to the Ground? Thanks!