Unity terrain adaptive or LOD wireframe problem

Recently I am playing with unity terrain. I found out performance of terrain is pretty bad compare to a same size and same shape mesh. The draw call of terrain is 10 times of mesh. I want to know what happened about unity terrain so I compare it with Unreal terrain. The Unreal terrain is much faster in fps.

Then I found out Unity terrain seems act wired with “terrain adaptive”. When I move my camera, terrain wire frame changed nonn-equally(wire frame appears like chunk and in different places Not as smooth as unreal.)


How come this happened? I think that is the main performance cost of Unity Terrain…

Hope anyone can help.
Thank you.

anyone?

Unreal Landscape is very similar to GPU pro3 's method. And Witcher 3 style.
Unity has 20years ago styles.