Overall Visibility (CPU/GPU): Use about 2700 as High, 2150 as Standard or 1600 as a Low setting.*
Object Visibility (CPU/GPU): Use about 1600 as High, 1350 as Standard or 1100 as a Low setting.*
Shadow Visibility (GPU): Leave at 100 or lower.
Brightness: Up to your personal preference.
Gamma: Up to your personal preference.
Rendering Res: Set this to 100%, don't try to be cheap and lower this value as it will only make it blurry.
VSYNC: Set to DISABLED unless you are experiencing screen-tearing or somehow have a high spec 60+ FPS computer.
HDR Quality (GPU): Low has better performance.
Anisotropic Filtering (GPU): High to Ultra, will most likely not impact or increase performance.
Antialiasing (GPU): Set to 2x, 4x or DISABLED, 4x is generally better performance but may make your scope lag.
PPAA (GPU): Use FXAA High to Ultra, Ultra will likely have the best performance.
AToC (GPU): Set to DISABLED or Trees only, Grass may make your scope lag.
PIP (GPU): Low or DISABLED, while better than it was previously keep in mind that it still consumes a lot of frames while driving for a cosmetic effect.
Dynamic Lights (GPU): Low or High, Ultra seems to have no effect on frames but is probably not good on older graphics cards or in multiplayer.
Postprocesses (GPU) Low, Very Low or DISABLED, up to you.
Texture Quality (HDD/GPU): High to Ultra, High stops a lot of the building pop-in Ultra basically eliminates it.
Objects Quality (CPU/GPU): Standard to High, having this on a higher setting will reduce pop-in from terrain features but comes at the cost of frames.
Terrain Quality (CPU/GPU): Standard to High, higher means more frame lag for not much gain visually or otherwise.
Cloud Quality (GPU): DISABLED, you are on the ground not in the clouds plus it stops them from rotating.
Shadow Quality (GPU): DISABLED or High+, lower settings seem to be worse, Ultra seems to give best performance.
Particles Quality (GPU): Standard or High, Ultra seems to have no effect on frames but is probably not good on older graphics cards or in multiplayer.