jewelbyrnes Does this happen if you enable object hiding? Please change the setting at the Main Menu, and quit to desktop before loading a save.
If this doesn't help, how far are you getting into your saves, in sim-days? Does the same thing happen if you play in Sunset Valley? Appaloosa Plains is generally stable, but there are a couple of issues that can cause performance to drop or even trigger a crash under the wrong circumstances. For example, baby animals can't navigate stairs, including the stairs in some of the homes where they live in AP.
It's also worth pointing out that custom content can be the issue even if it causes no problems right away. Some cc is fine until a sim is actually wearing it, or the wrong sim is wearing it.