Why does the Sims 3 pets keep freezing?

Its usually because you have a lot more on one set. If you have a multiple stories, music playing and/or more than 4 characters, your PC is trying to configure all moves. It could also be that you have other programs open while running your sims game. If any of these still make it freeze you may need to delete some unused files from your computer. This will make all of your programs, whether games, music, or just Surfing the web a lot faster.