Okay, it's not Isla Paradiso by any chance, is it?
The reason I ask, is because that place is notorious for lag. If you are already using mods, I recommend installing Nraas Overwatch, Error Trap and Register. Once you have them, click on the city hall and select Register, then go to animal control.
Reducing the number of wild animals will help a LOT. Some worlds have pretty nasty routing issues, and having 6 horses, several deer, several raccoon's plus all the stray dogs and cats running around can play havoc with your system.