lighting for the vault tec dlc is terrible. whenever i'm building there i use SOE by ccmads which adds some great options for lights in general but they're perfect for vault 88 imo. you can choose how far light will be casted with ranges from i think 1-4 floors. when installing, you'll get an option to enable shadows for lights or not. i personally would recommend not using the light shadow enabler since as dragonslayer said, it's a disaster for performance, but you could always give it a shot and see how things are running, and if it's hurting FPS too much, just reinstall and disable shadows. hope this helps I am going to try this mod right now. I hope it works. I really want it to have ambiance.