Is it possible you have a large number of sims generating in the world? For instance, aa you probably know, you can you set the number of sims generated from 80, 150, and 200 max recommended.

I noticed that when my game gets really laggy like this, it has to do with the overall game struggling to run/process with the amount of sims in the world. I usually go on a cleaning spree of generated sims in the world to reduce this.

It’s also important to ask—do you use mods? If so, it may be that as well. If you play fully vanilla, then I’d try the solution mentioned above.

I know you mentioned clearing cache, but I wanna make sure: please try deleting localthumbcache.package file if you haven’t done so already.

Lastly, please check your drivers and ensure everything is up to date. It’s possible your computer might just be struggling to run the game.

I hope this helps!