When moving around on the ground with textures set to the highest setting you will see parallax occlusion mapping on the terrain, while it can be a nice visual feature, it also serves to annoy and even creep out in some instances due to the fact that as you move the ground warps around you.
The feature is there obviously but it needs the range of being rendered to be extended by using prone as a guide, otherwise it's more of a visual oddity than a compliment.
As it stands it's more of a tolerable feature than a great feature, and if the concern is due to performance then POM should be a tick box as opposed to grounded into the texture detail.