The game launched in 2010, but the Gamebryo engine it is built on is even older, and there’s only so much mods can do to improve a title (Gamebryo also gets a little grumpy if you try to keep stuffing visual improvements and improved textures into FO3 / FNV).
At the same time, there’s no denying that New Vegas is beginning to show its age. The plot of the game takes inspiration from the original, Black Isle version of Fallout 3 (codenamed Van Buren), and it builds on elements of the in-game universe that were introduced back in Fallout 2. Fallout New Vegas is arguably the best of the three modern Fallout games.