Oh dear, it sounds like you forgot to delete your caches--this can be done by dragging the Game/Bin folder for the base game (Sims 3) over to the trash bin and deleting it. That should reduce the load-time and prevent your game from crashing.
That's kind of mean.
Sorry, but killing and eating my broodmates seems to be
de rigueur around here, especially if they can't do a search for their own answers.