Hi,
One last question, I also have a drop of fps when looking far, at the horizon.
Each landscape component is a separate draw call. With the settings you have used there are 3000 components, if you do not stream them by distance then looking at the horizon would be hundreds of them that need to be drawn, whereas if you just look at the ground there is only a single component that needs to be drawn. If you would remove the landscape and just use a single plane (scaled to the landscape size) then I would expect nearly no difference in performance whether you look at the ground or at the horizon.
For the grass, consider disabling shadows (you could use contact shadows instead if you don’t want unshadowed grass, but I wouldn’t use any ‘regular’ shadows, imo the cost vs visual impact is way too large for small foliage like grass). Also the cull distance used in the image is very large.