It causes issues when the interface pops up (e.g, recieving a message from another player) where many objects become fully transparent, and has caused issues for some users when ExpandSystemMemoryX64=true. I also recommend disabling the Steam Overlay for Fallout New Vegas. This means you can have VSync enabled without the framerate juddering between 15 30 60fps. Also, when a game is in windowed mode (Windows 7 and newer), the game gets triple buffering. So have New Vegas in windowed mode, and everyone's happy. And that setting is a game changer, as it greatly reduces stuttering if not completely eliminating it, when models and textures are being loaded (e.g, travelling across cells, transitioing from interior exterior). It's also required that you have New Vegas running in windowed mode, if you don't want to crash upon alt-tabbing with EnableUnsafeMemoryHacks=true. Vanilla Skyrim used over 1GB of VRAM, but it should be less with vanilla New Vegas. In order to get the minimum VRAM required, load up your game and play for a wee while, and look at the amount of memory used under the ENB overlay's profiler section. I've set them to use my card's 2048 MB of VRAM if you have more than that, set it higher.
In your driver program, ensure that your New Vegas profile has Anisotropic Filtering and Anti-Aliasing Mode set to Use Application Settings. I'll keep this as no-bullshit-y as possible.
