Irregular extreme lag on laptop

@Lysan20  An Intel HD 620 is not really capable of running Sims 4 on ultra graphics settings, at least not very well.  The lag you're seeing may be due to the chip not being able to keep up when graphics processing demands are high; other times the demands may be lower and you might not have any issues with those settings.

Still, it's not clear from your description that this is the issue.  Please play for a while and take note of what's happening in-game when you see lag or freezing: what sim-time it is, what lot is active, how many sims are in the picture, etc.  You don't need to get all the details; the point is to see whether there's a pattern.

Please also check your in-game framerates.  Bring up the cheats console (crtl-shift-C) and enter "fps on" without quotes.  A number will appear in the lower left corner, over the user interface.  Let me know what you see during normal play and when the game lags or freezes.

Finally, please run a dxdiag and attach it to a post.

https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/