Same thing happening here. I’m using a heightmap landscape with basically the same proportions as yours and a very simple material to paint the terrain.
CPU, RAM and GPU are ok, I’m checking the task manager.
Makes no sense 
Same thing happening here. I’m using a heightmap landscape with basically the same proportions as yours and a very simple material to paint the terrain.
CPU, RAM and GPU are ok, I’m checking the task manager.
Makes no sense