I especially agree with the MOO advice. I swear, I can not have it active for more then a couple minutes before it will start to cause big lag in my game. :\
There is a safe way to add old sims to your new games. If you added them to your library/bin in CAS, anyway. Then you can go into the SavedSims folder and pull the " .sim" and place it into the SavedSims folder of your new game. You would find them in the bin in CAS in your game.
The .sims are not the actual sims in the sense that they have any content attached to them, they are just kind of like a blueprint for the game that say, "this is how this sims should look". If you don't have the content that was on them installed, the game will replace it with a default one. You may have to re-do the traits and such, but appearance-wise they will be the same, to the limit of your content installed.
