@slyytherinnMost likely
1. Cause - errors of the files inside the game folder sometimes done by outdated mods and CC after the patch - try doing a factory reset as is described here
http://answers.ea.com/t5/The-Sims-4/FAQ-Troubleshooting-Steps-amp-Known-Issues/m-p/36211992. Cause - connection with internet - frame rate issue
Connection to the internet lowers the FPS rate. It is so low, that to play is near impossible
Disconnect your internet completely - turn off WiFi unplug the cable - when you are in-game and check if it makes any difference. You can also try to mark vertical sync in the graphics options and then restart a game. This should keep - according to other tips - FPS at 60
https://answers.ea.com/t5/Technical-Issues-PC/CURRENT-ISSUE-Incredibly-Low-FPS-when-connected-to-Int...If it will not work
3. Probably there are problems with your computer ( failure Windows updates ( get at least KB4505903 update what fixed frame rate problem caused by the system)
https://support.microsoft.com/help/4027667/windows-10-updateWeek graphic card, outdated graphics card drivers, software failures, the ventilation system is dirty and the computer overheats when it is working hard)
Could you post your Computer's DxDiag?
To gather a DxDiag on your computer, please follow the steps here:
https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/(Press the Windows key and "R" at the same time.
Copy and paste or type "DxDiag" in the new field. (Without the quotes) > ENTER
Wait until the green bar is gone > Click on "Save all information"
Save the file to your desktop)
Here at AHQ > click on "Reply" > click on "choose file" > navigate to the "DxDiag.txt" on your desktop. > select the "DxDiag.txt" > click on "Open"
Type a few words in the text box > click on "Submit"
I don't work for EA
