@zelneciaaaa Sims 4 has apparently become a bit more demanding, or at least a bit more prone to lagging, since the most recent patch. It might only affect computers that were already struggling to run the game, and it might have to do with the new neighboorhood stories feature; I haven't really looked into it. But it's possible things will smooth out again after another patch. You can also try turning down the graphics options to the absolute minimum to see whether it helps, and turn them back up one at a time from there.
If the lag gets worse, or you notice a pattern to it, let me know. And I'm still curious how much memory Sims 4 is using when the lag happens, as opposed to when it's running well.