Bubble_giggle24 Does this happen in a new save as well? Please test for comparison's sake.
If the new save is fine, please move your existing sims to a different lot in your main save, preferably a blank lot or a default version from EA, nothing from the Gallery or your own library. Let me know how the game runs in that context.
If the new save lags too, please provide a dxdiag. Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop. From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.