Sims 4 laggy all of a sudden.

@kiki_taco  Thanks for the dxdiag.  Most of the errors it contains are for failed Windows updates, so that's the place to start.  (Windows trying and failing to update while you were playing could also explain the game lag, but this should be addressed either way.)  Please run a couple of basic checks of your Windows system files:

• Hit Windows key-X
• Choose either “PowerShell (Administrator)” or “Windows Terminal (Administrator),” whichever option is offered
• Inside the window that appears, copy and paste “DISM.exe /Online /Cleanup-image /Restorehealth” without quotes, and enter
• The system will start validating soon. If it throws an error, please list it here
• After it reaches 100%, hit Windows key-X again
• Again, choose “PowerShell (Administrator)” or “Windows Terminal (Administrator)”
• Inside the window, copy and paste “sfc /scannow” without quotes, and enter
• Post the message you receive here

Restart your computer, hit Windows key-i, select Update & Security, and click the box to check for updates.  If any install, restart again afterwards.

Test the game again.  If you still get lag, test a new save with no mods or custom content at all, as in, move the Mods folder to your desktop and delete localthumbcache.package.  Today's update was small, but it could have broken one or more of your mods or cc items.  Since you're testing on a new save, you don't need to worry about missing content.