@iremakakca The world of Isla Paradiso has been broken since the pack was released, and the game can freeze or crash there on even the most powerful systems. It's not about RAM either, more the game engine falling all over itself trying to reroute stuck sims and the like. The workaround is to either play elsewhere or use a fixed version of IP like the one you can find here:
https://forums.thesims.com/en_US/discussion/811253/removing-ip-lag
You can also apply the listed fixes to your own save.
The issue with color blocks sounds like something within the game engine—a rendering function, clearly, I just don't know what the technical term would be—is failing. This is more likely to happen when the engine has too much to do, as would be the case on the festival grounds if there's a lot going on, including a relatively large number of sims. The fog that covers IP's hidden islands is also quite taxing: I've panned across the horizon and seen a 40% decrease in fps as the camera centers on one of the fog banks. So I'd guess that the rendering part of the game engine is just giving up.
As far as graphics options go, it seems that lighting and tree detail cause more problems than other settings; many people with integrated graphics need to put both of these on low. I don't necessarily think this is your issue, but if you see problems in Sunset Valley, it would be worth changing those settings.
P.S. Long answers are a good thing, that is if they have useful information, as yours does. It saves us both the time of all the extra replies needed to clarify the situation.
@iremakakca The fixed version of IP is a save that the user who made that thread has uploaded for other players to use. It's actually two versions, one with only base game and IP content and one with content from all packs, but both have been modified to remove the most problematic elements of the world. In either case, you would download the save and drop it into Documents > Electronic Arts > The Sims 3 > Saves, and it would load like any other save from there. It would be best to use "save as" the first time you saved after playing it so that the original remained intact, under its original name, for the next time you wanted to use it.
The player who provided the saves also documented her work for anyone who'd prefer to make the edits themselves. (That's also covered in the thread.) So if you'd like to fix an existing save rather than abandoning it, you can copy the edits she lists.
It's still a good idea to use a few NRaas mods when playing in even the most heavily repaired IP, particularly ErrorTrap, Overwatch, Register, and Traffic, to clean up or limit a number of issues that you'd otherwise see. MasterController's reset functions are also highly useful. More details are here:
While the Mac version of Sims 3 has its problems, none of the details related to IP itself are specific to this version.
@iremakakca I personally wouldn't play in any world without mods. The vanilla game doesn't have any cleanup routine for corrupt or stale data, it can produce far too many service sims or vehicles, stuck sims can drain resources... the list goes on. The problems are more pronounced in worlds that have other problems because the game engine can only handle so much at once—a higher baseline load means it takes less extra work (from corruption or the like) to push it over the edge. But even in the most well-made undemanding worlds, you'll come to that edge if you play the same save for long enough.
As far as guides go, this is the standard for how to install mods:
https://modthesims.info/wiki.php?title=Game_Help:Installing_Sims_3_Package_Files/Setup_and_Files
The list of mods I'd recommend is the same one in the thread I linked, basically NRaas ErrorTrap, Overwatch, MasterController, Register, and Traffic, and Traveler as well if your sims ever travel. Other than MC, these mods do their cleanup in the background with no user input and no need to change any settings; MC doesn't do anything at all unless you use it to issue a command. So you won't notice any gameplay changes, just the occasional message from ET or another mod notifying you of some basic cleanup.
All of these mods have been thoroughly tested over a decade, they've been downloaded literally millions of times, and none of them will damage a save, let alone your game overall. The mods themselves are still supported on the NRaas site, so if you do notice any issues, you can get help from the developer or other support staff.
As to whether you're better off abandoning this save, that depends on how much you care about it. You can always save your active household to the in-game bin and place the sims in a new save: they'll keep their skills and money, their relationships with each other, and their careers provided the required rabbitholes are present in the world when the sims are placed. If you don't mind starting their outside relationships from scratch, it's certainly a reasonable option. If it would make you sad to lose the rest of the town, then it's probably worth trying to fix this save.
