You haven't mentioned what maintenance tips you've tried to fix the issue, so please forgive any repeat tips.
1. Turn off Origin In-Game:
Open Origin, Select Origin > Application Settings > Origin In Game tab and click the on/off switch to disable Origin In Game. - This deactivates Origin In-Game, as it has been known to cause problems with games.
2. Repair Game:
In Origin > Games Library, right-click on Sims 4 and select Repair. - Do note this repairs the game's install files for the actual game. It does not make any changes to the saved game files. Meaning that your saved games are safe, they won't be deleted. If you'd like you can copy the Sims 4 folder to a USB key, for safe keeping.
3. Empty Sims personal and family inventories. Often too many items in the inventories can cause issues. - Also, having a large family and house with a lot of furniture/decor and landscaping will cause lag after awhile.
4. Reset Sim and/or Household - Have them travel to a different lot.
resetsim [firstname lastname]
Have them all travel to another lot, and then send them home. This should reset all family members. -- * Use the M key for map, for fast travel.
5. Delete the game cache and localthumbcache.package out of the Main Sims 4 folder.
http://www.carls-sims-4-guide.com/forum/index.php?topic=29288.msg401662#msg401662There are more tips in the post link below.
Relieve Freezing and/or Game Lag
http://www.carls-sims-4-guide.com/forum/index.php?topic=29313.msg426179#msg426179