I'm currently playing a big world right now. At first, it's fine. But as I'm playing more, the problem is starting to occur and the game is starting to slow down.
I think the problem is the stuck sims somewhere in the world, that slowing down everything, and because of that, the glitch is starting to appear. Like stuck on the floor, inside the wall, etc. The slower the game, the more glitches produced. It's like KW is trying to start an interaction, but because the game runs very slow and the player, plus autonomous interaction keeps giving commands, bombarding the system, the oldest command will be forced to stop, and a scripted interaction like KW, sometimes it's not stopped, but stuck. It keeps happened thru time and mounting along with other problems to the level it's unplayable.
I think that is how so many people say that KW is buggy, while actually it's TS3 system, plus KW is just adding more burden to the already bothersome system. In the end, firing back to KW itself.
The only solution for KW is stopping adding more features (which is we don't want to happen) and cutting down the old features or make it simpler (as long as it doesn't effect the original gameplay that is already great).
Playing a small and simple world, the problem is much more controlled, KW is almost a bug free.
More sims, more family, wild animals, more lot types and more complex house design in the world also add more burden to be processed, until there's no room or a very little room for KW interactions.