lulumisya Moonlight Falls runs reasonably well, so the world itself shouldn't be an issue. How long have you played this save? Do you use mods, and if so, which ones? It's fine if you do, in fact some of them are very helpful, but I do need to know what you have installed. If you don't use mods but are open to adding some, let me know and I can make suggestions.
Please also describe the lag in more detail, since there are multiple symptoms people describe as "lag" that don't necessarily have the same underlying cause.