@Nasdrah Sims 4 has fps drops, that's normal. Framerates will be lower in some worlds than others, for example San Myshuno makes fps drop considerably; bad weather, like rain or snow, requires more resources to render than a sunny day; and more sims on a lot will also make fps drop, sometimes considerably. High poly (high resolution) custom content can lower framerates as well, since it's more demanding to render than EA-made clothing.
Are you seeing any other issues in your game? Is there a pattern to the fps drops, for example in a certain world or on a certain lot? If you use a lot of custom content, try playing without it, just to see whether it makes a difference. You don't have to save your progress.