As a roblox developer, it is currently too hard to make a large open-world game without every client dying of lag spikes & FPS Drops. No game engine is powerful enough to run a large, 100 player server, open world game on a potato at 30-50 fps, so how do they do it? LOD Models. For those unfamiliar of what an LOD is, it’s essentially a lowpoly mesh that resembles a higher poly mesh at a distance. Essentially, you’re substituting a shape of a mesh for a complex polygon when the player is far enough away. High poly meshes contain lots of triangles, and though every mesh on roblox is under 5000 triangles, there is still room for improvement. Reducing a 3000 triangle building down to 12 triangles and a texture can have an extremely large impact on the performance of a client’s personal potato. I also have noticed that ROBLOX already has recognized the power of LOD models, using it with smooth terrain in order to improve overall performance.
Example of LOD Meshes:
The mesh on the right is what you’d see if you were standing directly next to the box in-game.
The mesh on the left is what you’d see if you were looking at it from the opposite side of the map, through a pair of binoculars for instance.
Clearly, the mesh on the left will have a much softer impact on your graphics card than the one on the right 
Hopefully we can see this in the future! I think it would be a really neat advantage to have on mobile devices. Thanks,
-big
Note: perhaps this should be able to be toggled by the developer? Some places run well even with high poly meshes, and we shouldn’t take quality away from those games if they’re already working fine.