There's a way to do this but theres one problem, and this only happens in Arma 3, you can't see text, its just white boxes.
But you can still try it.
If u have an Nvidia GPU install the Nvidia Profile Inspector (I use NVidiaProfileInspectorDmW), on profiles search for Arma 3;
On "Antialiasing - Transparency Supersampling" choose "0x00000008 AA_MODE_REPLAY_MODE_ALL";
On "Texture filtering - LOD Bias (DX)" choose "+15.000";
(Not certain if this one is necessary) On "Texture filtering - LOD Bias (OGL)" choose "+3.0000"
Save changes
Run Arma3
Now the graphics should be potato
This actually removes a lot of grass and clutter where enemies could be hiding, its also easier to see enemies from afar and when they're inside vegetation
Give it a go.
(This also works on other games, like Rising Storm 2, it works perfectly there)
If someone can figure out how to get rid of the white boxes let me know.