It has been a while since I've modded Fallout New Vegas but if it is anything like back when I did it you need to be really, really careful if you seriously mod it because the game is already seconds away from bursting into flames and crashing at any time before you even add mods to it.

There are mods which improve the stability of the game considerably but at least back in my day adding too much on top of those was a game of fucking around and hoping you won't find out.