Operating System: Windows 10 Home
Processor: Intel Core i7-5500U @ 2.4GHz
RAM: 8 GB
Graphics Card: Intel HD Graphics 5500

I keep all of the graphics settings on minimum except for Sim detail, which I keep at max. I hardly ever get any lag when I play this game.

On one of my saves, I have a household of 8 Sims. For 7 of these Sims, I experience absolutely no issues whatsoever, but when I select the 8th Sim, I start getting tons of lag. The mouse cursor takes about a minute to change depending on what I'm mousing over, zooming and rotating the camera take ages and are very choppy, and menus take about half a minute to appear after clicking something. I have had NRAAS MasterController for a while and also downloaded Overwatch a few minutes ago; Overwatch has given me a notification that the specific Sim giving me issues is "unroutable," and I have used MasterController to reset the Sim multiple times, but it doesn't change anything.

The Sim does not have any CC on them; no CC clothes/hair, no CC items in inventory, no CC traits. None of the CC I have has caused any trouble on any of my other gamesaves.
The expansion packs I have are Ambitions, Late Night, Pets, Supernatural, and Seasons.

Am I just going to have to delete that Sim or can I fix this?

sorry for the bump but i do have an update.

it turns out the lag was caused by an item in my sim's inventory; i know this because after clearing everything out of it (the sim was carrying upwards from 2000 items, all fish and plants from base game + ep's.), the lag stopped. i've been able to pinpoint a specific type of object as well. as soon as i put all of the glow orbs i had back in the sim's inventory, the lag returned, and while i was planting glow orbs, one of them caused my game to crash. all i need to do now is find exactly which of the 46 glow orbs i have is the one causing problems.

so i know i have at least one corrupt glow orb that i'll be deleting. the lag wasn't quite as awful as it used to be, so i suspect i have more corrupt items.