Frame drops Unity 5.3.4f1 64bit DX11 and DX12(beta)

Hi,
is there a option or something else to reduce the frame drops?
The game runs with over 100 FPS that’s ok, but if i rotate the camera the frame drop down to 10 between 30.
Have anyone a idea, how can i fix this.

best regards and thanks.

Both screenshots show 120 FPS, so what’s the problem?

The problem is only if i walk with the player through the scene and rotate the camera. If the camera still i get over 100 or on a other position over 200 fps.
But the same problem, if i rotate or walk fast through the scene for a second the frames drops down to 10 or 30 fps.

Hmm… okay, if i disable the terrain details (Grass) complete, it runs perfect.
but if i reduce the detail denisty a little bit i get the same problem.
how can i fix this?