Are you sure? Take a before and after screenshot.
Also make sure your setting change isnt being reverted.
Yeah, I'll take screenshots in a few. but... I noticed it was being reverted when I use the launcher. so I just started using the main FNV exe... but... i dont understand why there isnt more GPU usage, if i increase the Distance LOD
Edit: I didnt notice much, so I actually shot it up to 25. and it took FOREVER to load and then it just crashed, so OBVIOUSLY that's no good. so i dropped it to 15 .. and the only thing that happened was framerates dropped to the 40s... no noticeable difference.
This should be affecting the world loading farther away right?