The first issue you mention is a common symptom of severe corruption: the game isn't able to load all the save data and instead loads an empty house. The only thing you can really do is revert to a backup save.
For the second, this could be a performance issue due to the world or to your computer. How much RAM is the game using while you're playing in the world? You can put the game into windowed mode and check in the Task Manager. What hardware does your computer have—processor, graphics card, RAM, free and total storage—and if you have a discrete GPU, have you taken steps to manually limit the in-game framerates? That's not all of the possibilities, but it's where to start.
