Hi chingwa, and thanks! GPUI Tree and Detail managers were designed with the idea that each manager would be responsible for a single terrain. This results in managers that are not aware of each other, so even if there are shared prototypes in different terrains, the managers make separate drawcalls for them. Therefore you would indeed get a better result (in terms of rendering) if you have prefabs defined in the prefab manager instead of terrain prototypes. And even better results if you use a no-game object workflow (but you would have to manage your colliders). Currently, an optimization for "multiple terrains", along with various other features which will redefine how GPUI handles Unity terrains is indeed among our plans. However, these require fundamental changes to the core GPUI code as far as detail and tree instancing goes and thus will require a relatively major update - potentially one in which we will deprecate the Detail and Tree Managers and GPUI will use a single manager to handle everything related to the Unity terrain(s). So at this point I cannot give you concrete information on when and in what form these changes will be implemented.