Apparently, it was not widespread knowledge when the SimGuru's, at the time, would post information about how to maintain a save. I do not remember the topic or blog but remember seeing it so late after TS3 was done. However, this may help if you have not already read this:
https://www.nraas.net/community/TIP...AME-PERFORMANCE
Also, try checking where Sims are getting stuck or having routing errors so it can be corrected to prevent the save from lagging. For example, I downloaded a community lot called Rocket Red's Arcade by caterpillarsims and noticed when I placed the lot on the same size lot, Sims would get stuck because the parking spaces were at the edge of the lot where Sims would route fail. That caused my game to lag and to eventually crash to desktop until I fixed it. So just like Isla Paradiso, one of the main culprits is usually routing failures. While resetting Sims and/or the whole neighborhood might help temporarily, it is only but a short-lived fix if the root cause is not addressed.
It is common to read that saves do not last long and Sims have to be moved to a new neighborhood time after time. I believed that once upon a time, but got tired of that and figured TS3 cannot be as badly optimized as some claim. Where there's a will, there's a way. Understanding that TS3 is the most complex Sims game to date is key, therefore, requires a lot more player maintenance in order to ensure a save is running at its optimal performance. From what I notice thus far, TS3 has two major issues that is either developer or player based. One is when objects stop functioning and become broken such wall stereos, doors, mini-fridges, etc. So when Sims keep trying to interact with certain broken items, they can get stuck in a loop. Two is when Sims route fail because of the poor design of the layout of a residential or community lot. And sometimes for some odd reason, the game may just reset a Sim somewhere unroutable.
Issues I consider not a game problem but a player problem depends on playstyle and so on. Such as using high-poly custom content, mod incompatibilities both known and hidden/not up-to-date/wrong patch level/poorly made and optimized, too much custom content which has to be loaded up and slows down CAS/Buy/Build modes, using reshaders/HQ mods, etc. Each computer depends on what it can handle in terms of population, however, TS3 is a 32-Bit application and cannot use but so much memory. All those Sims and anything and everything that the game has to remember and load about each one likely takes up more memory usage. Not to mention, each Sim is being constantly calculated whether in view or not because that is one of TS3 main features is Real Time Simulating. Every single human Sim and every single kitten/cat, puppy/dog, foal/horse and likely deer and raccoons too count. The more strain is put on the game engine, the more performance drops. Because TS3 is from 2009, it was not designed and built to take advantage of gaming computers. Intentionally so, because the developers said they wanted TS3 to be accessible to as many players as possible, hence 32-Bit and the claim, "You can play on your grandmother's computer."
Currently, my longest save is at 226 weeks and day 2 for Moonlight Falls. It takes trial and error for me to keep playing the same save but so far so good. And now I do the same for all my other saves as well when I manually move my Sims around to different neighborhoods to manage population. Personally, I prefer around 80 Sims or less. Typically, I have little to no lag once I clean up my mods folder and maintain the saves. It's nice to fast forward using speed 3 for not just days but weeks and my game is still fine, plus the Sims are quick to take care of themselves and the little ones without my intervention. Not my usual playstyle but I am kind of rushing this round at certain intervals.
Previous Game: Batman Arkham Asylum GOTY Edition (100% riddles completed; now I know why I've always been fascinated with The Riddler, lol.)
Next Game: Batman Arkham City GOTY Edition