Hello! Man, it's been a while. I used to no life TS3 like 4 years ago. Long save, probably ran for 240 Sim Days. 3 Custom worlds linked.

I reinstalled and thankfully I had the save backed up in an old HDD. I was playing in RFlong Beach City but the lag and stutter was too much. So I moved my essentials to SimLua Isles. The game started to stutter and lag. The stutter was happening paused as well while moving the camera. I did:
-Clean up saved files with S3PE
-Have all the essential NRaas mods. 
-Fixed texture memory override and game not recognizing card. (GTX 1080Ti)
-My other specs are 16GB Ram, i5 4690k 3.5 GHz, SSD.

It seems that a major problem is my sole main Sim that I play. He has over 150 known Sims in the relationship panel. I cleared most of his inventory, but the real kicker seemed to be the amount of known Sims from other worlds. I cleaned like 30% of it via Ctrl + click. The game immediately ran much better. Is this a known issue? I've read the performance tips over and over.  I'm still struggling to find all the routing issues. I've modified pet automated actions to stop lag causing actions. It still stutters a bit when paused but much better. Any advice? My world has 105 service Sims and 27 residents only. 

PS: Pardon any errors, quickly written from phone at work lol. Thank you!

I would have to say that any real impact of having excessive numbers of sims on the relationship panel would be debatable at best unless we're talking about thousands of them.

But there might be something else interfering with the game's performance here. You've mentioned formal card recognition and getting rid of the texture memory override which are great steps to take, but much more important than that would be tending to the frame rates. Left on its own, your card will throw frame rates into the high hundreds or even thousands because TS3 has no functional fps limiter.

Have you taken the usual steps with the Nvidia Control Panel to set vertical sync and, if necessary, Nvidia Inspector or some other tool in your toolbox to cap the fps explicitly to the refresh rate of your monitor, and have you verified that the rates are staying locked in as you play and move the game camera around? Most monitors are 60 Hz, so the limit should be 60 fps. Some can run higher. To see the actual fps rates in-game, ctrl+shift+C to get the cheats console and type fps on (enter). To make the display go away, cheats console again and fps off (enter).

Hey igazor, thanks for the reply.

Yes, my FPS is capped at 60. Also worth noting that as soon as I started deleting relationships the game got progressively faster and smoother, suddenly there was barely any stuttering while paused. Also if in the same save I swapped active households or deleted my current one, it would run much better. I believe my Sim had a bit over 200 known Sims and of course opening the panel would freeze for a second or 2. Over 70% of those Sims are in other worlds whether it be custom maps previously played or Uni/WA maps. 

Then I would say you already have a better handle on what is/was causing performance disruption than many players already. The way to test the relationship panel theory further of course would be to work only with newly created test games and see what happens with sims having RPs that have 200+ foreign sims in them vs. those who don't. But it would probably be much more fun to forget about that and enjoy playing your existing game. Is the overall performance at least tolerable now?

And it would be remiss of me to not point out this page that lists many suggestions for improving the game's performance in case you haven't already seen and are using it.
TIPS-FOR-BETTER-GAME-PERFORMANCE
 

Ah yes, that link is a life saver!

You are right though I could test that, although I'm afraid many other factors influence the stutter and lag I get. It is tolerable though. It seems to be linked mainly to my current Sim and well, the routing issues that I keep monitoring. (My pets for example wanting to doggy swim constantly in a 1x6 fountain) I'll keep testing on the go. Thank you!

Just got home finally, lol. I did have a quick question, if only because I find TS3 to be one hell of a monster when it comes to its functionality and well, wanting to keep the game running relatively well.

My question is, what are things that could go wrong with a single sim that could cause lag/stutter? 

So far the only thing I've found is issues with inventories. Is there anything else that could go wrong with your active Sims after extended playtime that could hurt performance overall? I find it fascinating that my single Sim was making my game stutter more than any other Sim in town in the same save.  

I have terrible lag/stutter when sims have lots of scrap in their inventory. As soon as I remove it, they're ok, and other sims in the household or world are never affected. Also get lag when inventors are using the workbench if there's a really big amount of scrap in it. If I switch to another sim everything works normal, as does the inventor sim when doing anything else than interacting with the bench while selected.

I know you wrote you'd cleaned most of your problem sim's inventory but thought I'd at least mention it just in case. 

Thank you Wooly. Sadly that isn't the issue and it came right back. I guess it is tolerable but the constant mini stutters get on my nerves. But alas that's how it is specially on long saves.