The Landscape Demo has an with the 980 actually (it might be related to your as well), I can only get ~20fps with my GTX 980 and others have reported the same. It’s not overloading the GPU, it just won’t allow the GPU to use it’s full power for some reason. Some areas I can get up to 90fps, but in the middle of the map around the frozen lake I struggle to get 20fps and my GPU usage is sitting at 15% (when I got 90fps my GPU was at 75% load…)
Here is my AnsweHub post with some more details on :
https://answers.unrealengine/questions/141292/landscape-mountains-demo-low-performance-on-gtx-98.html
I don’t have issues with Landscapes outside of that one project, but I haven’t tried using any other landscapes that were imported from World Machine, so I am not sure if it’s the landscape or what. I’ll let you know if I hear anything back from epic after they have completed the testing on their end.