There is/was a pathing issue with Generations.
If the game is locking up for a few seconds, and it's doing this repeatedly (and it's making your blood pressure go up), it's usually because someone, somewhere, is stuck, and it's making the game freak out. There are two solutions.
The first is definitely a bit more cheaty, but it's fast. In the command console (shift + ctrl + c), type "resetSim *" without quotes, case sensitive, and hit enter. This will reset every single sim in your town (this will lock the game up for a couple seconds), meaning all sims go home, and all moodlets are reset to full, except fun which goes to half.
The other way to do this, which prevents you from performing the reset on your own sims, is to actually go out and find the stuck sim. Generations built houses, all of China, fences, the Doll house are all potential troublemakers. The stuck sim will be the one standing there never doing anything. If you can find them, you can reset them (resetSim [lastname] [firstname]), and potentially edit the property to remove issues.
I can't remember if this issue was ever fixed. The discussions I have found on it are from last year, prior to the latest patch and EP's, so this might not be a valid issue now, or it might still be a potential problem for anything with Generations.
