NRaas mods that help with performance overall: Overwatch, ErrorTrap, Register, Traffic, to an extent GoHere, Traveler (if you ever travel your sims), MasterController for an occasional MC Reset of the actively being played world. The others for the most part add or extend elements of gameplay.
But yes, a fixed up version of Isla Paradiso is required with or without the mods to be playable for most. The world is too design-flawed "out of the box" to be played as is.
Here is how to get started with package based content like mods, in case that information is needed.
http://modthesims.info/wiki.php?title=Game_Help:Installing_Sims_3_Package_Files/Setup_and_Files