Performance is a foundation for a games success.
You can tweak and optimize a game all you want but if you keep piling more and more things into one option you're going to run into bottlenecks at some point.
For a game to be open to the widest variety of computers it NEEDS to have a great deal of options for performance enhancement.
As it stands Arma 3 has several but far too many rely upon one another to really benefit.
For example post processing covers; bloom, depth of field, ambient occlusion a blur filter and more.
Blur and bloom are tied together then comes DOF and finally AO.
Bloom is a great feature and compliments the HDR nicely but it can be aggrivating due to the blur.
DOF is nice but it still relies on the previous two and as such eats up more frame rates as is AO.
Terrain details are another huge hit. With deformation, grass clutter plus distance.
Grass alone is a huge hit but you are combining the amount of grass plus distance, in the end it causes the effect to be more demanding than it needs to be AND screws over the terrain deformation on higher settings.
Texture details are another big one. Special textures such as normal require a great deal of memory versus their diffuse counterparts, twice as much in fact! Having the option to disable rvmats on the lowest texture setting or it's own check box would save MANY people a great deal of frames.
Secondly if you wish to have the highest resolution of textures you must also force your computer to run Parallax Occlusion Mapping, another hog and when combined with full resolution textures, can do more harm than good.
Since POM is a very specific utility, having it optional would be better than combining it with an already demanding feature.
Lights with hotspots and falloff, a more vibrant core and authenticity yet shadows are nowhere to be found, sad since it leaves the feature half baked.
Especially when you consider that indoor combat is a huge possibility in A3 and these lights could create all variety of lighting from calming to eerie.
This could be one of those tick boxes, allowing the USER to decide wether or not their computer is capable (or forceable) to render these.
Further concerns could be addressed by adding a variably for light entities that are not tied to vehicles and flash lights, "iscastingshadow=0" or something like that.
Take for example the carrier mission from Crysis 1, with vast numbers of lights upon the carrier deck.
Despite these being actual lights, nearly none of them are actually casting a shadow thus saving performance while allowing the necessary ones to do so.
Separate Object, Foliage and Flora.
Tree and grass are always a big hit in every game, many go around this by setting the render distance to short, blending the grass to ground or separating the options. Arma 1-3 have all made the mistake of compounding this into one option which EATS frames depending on the scene.
Because of the grass clutter and distance alone, setting terrain and object detail to ultra can potentially devour frame rates.
PIP & Shadows. The difference between PIP's setting is marginal once its on, a bit of extra view distance and that is it with little loss in frame rate.
Lacking of PIP shadows also harms it just the same as lights. Again this could become an option setting that would allow those with more powerful PC's to decide how they want to view things and others to tweak it how they need.
Versatility is the name of the game, and what a player wants out visuals will vary based on the environment. Are you driving through a closed off city with very little in the way of greenery? Are you fighting in a forest? A tunnel? Is the scene day or night? What mood are you trying to set?
Having more varied options would allow both player and developer to expand on scenario's and game modes, but more importantly having more varied options would allow more people to run Arma 3.
In conclusion here a rough draft of the more versatile set.
Grass (Flora) Clutter -detail
Grass Distance -detail or slider
Terrain -detail
Terrain Relief On/Off
Shadows -detail
Dynamic Shadow On/Off
PIP On/Off
PIP Shadows On/Off
(optional) texture detail low= no rvmat
(optional) Texture detail and special textures separate, allowing users to high the highest resolution textures without using the normal maps, great for cards that do not support advanced shaders.
Object detail (people, guns, houses, props)
Foliage detail (trees and bushes)
DOF On/Off
Ambient Occlusion On/Off
Post Processing (lower setting allows bloom and higher allows blurring)
The rest I don't mention because they are mostly fine as is.