This interesting. I recall that most unreal engine games had the tendency (only if you look closely though) to have objects that seem to have no texture or lets say what I call a texture load lag. This is particularly true when you are rather away from a far object. if you get close enough and abruptly you will notice the game is trying to quickly stream in the texture map to hide from the player that not all objects have their textures loaded in just yet to save performance.
They idea is in FPS when you are fighitng you won’t have the time to pay close attention to all the graphic details cause this can mean lose in battles. Its a good strategy to save hardware resources while minimizing noticeable losses in visuals.
This is a common tweaking techniques gamer uses. it was very helpful multiplayer games. I do play world of warcraft and found that reducing distant ojbect details was great help as in raiding you won’t have the luxury to pay attention to the visuals.
This might be counter intuitive when you are playing an exploration game like skyrim or Crysis since most of the time you are paying attention to the surrounding vegetation
Typically games term it as Level of details or game detail and offer the abilities to choose between. low, medium, high, very high. So probably these correspond to A,B,C,D respectviely
Also back when I was understanding the concept of tweaking games I ran into this concept in this article
http://www.tweakguides.com/NVFORCE_7.html
Under the topic
Texture Filtering - Negative LOD Bias
Borderlands 2 have Level of Detail option (called Game Detail to avoid overwhelm for end users). which is further customizable by editing the ini files of the unreal engine as explained here.
http://www.geforce.com/whats-new/guides/borderlands-2-borderlands-the-pre-sequel-tweak-guide#8
Also lot of unreal game engine allows you to actually edit the ini file for further control beyond optioned offered in game setting
Most gamers tend to have quite attitudes against tweaking with the “its just the hardware” mindset but for those who have understanding of the graphics concepts especially those who are involved in learning 3d modeling well understand the importance of optimizing the settings/variables in the 3d application
Even if you are not a developer having a basic understanding of these concept still very beneficial to get the most of your gaming even if you have the highest end hardware.