Speed Island 2.52

I am under the suspicion that the main mountain textures were causing a drop in performance while in parts of the camera range.

-Reduced main Mountain textures from 4k to 1k in the hopes of improving performance. There is some more detail now to the large Mountain with an optimized texture resolution.

At this stage any performance issues may be due to the lights in the world.
If you use world editor with F11 you can delete the auto_lights group in the scene tree.
That will delete all of the lights as well as the automatic lighting.
That can help increase performance if it is needed.