I actually remember them talking about that a long time ago in a reddit comment. I think it was something like having to dedicate some kind of shaders to the entire game world rather than just sections they please and it'd be time consuming and somewhat of a waste of resources. I'll try to find the comment. EDIT: Found it. Entire reply is in Spoiler section or you can check it yourself on the reddit link I shared up top. [spoiler]You are correct. Shadow casting dynamic lights are quite expensive to render. We design flashlight areas with explicit rendering performance in mind based on a full fireteam using flashlights. Conceivably we could build a flashlight-specific rendering heuristic so that they drop out when not in a traditional flashlight space, but that is not low hanging fruit. I personally would prefer to spend resources addressing areas that are considered to be unplayably dark, regardless of black/white point/brightness setting.[/spoiler]