...is this what you are desperately searching for...;)...>>>
Terrain detail:
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TERRAIN_MAX_AUTOGEN_TREES_PER_CELL=4500
TERRAIN_MAX_AUTOGEN_BUILDINGS_PER_CELL=3000
Try reducing the above figures by 50% and see what a difference it makes, then tweak upwards till you are happy. The maximums for these values are 6000 (insane amounts of detail) and the minimum is 0 (no trees or buildings no matter where your sliders are set)
FIBER_FRAME_TIME_FRACTION=0.25
TEXTURE_BANDWIDTH_MULT=400
WideViewAspect=True
TERRAIN_MAX_AUTOGEN_TREES_PER_CELL=2300
TERRAIN_MAX_AUTOGEN_BUILDINGS_PER_CELL=1300
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Cheers....

...!
Paul....busy cutting down trees, and blowing up buildings...

...!
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.