[2020] Broken Asset: QB1: LOD xys (not findable??)

The error "LOD xys null" shouldn't be a huge deal. Does the Loading Screen Mod report the asset as broken? Otherwise I'd just ignore it. It's basically just saying that the particular building's LOD model is missing a specular/normal map combined texture. This is a really minor thing and shouldn't break the building on its own.

A completely black and/or very shiny LOD usually means the model's UV map is outside where it should be. Basically the LOD ends up with a texture from another building/prop, which is why it looks weird. It's best to avoid buildings/props that do that, as they can mess with other LODs. They will have a different error though. :)

Having a mod doesn't affect performance outside of what it does. It isn't like assets where it takes up X amount of memory from just being there. Instant Return To Desktop is a very lightweight mod, but if you're fine with shutting it down through the Task Manager, then the mod won't make a difference for you. It's great for everyone who's not comfortable with that though.