Remedy gives there the Mod Overwatch, they always cleaned up the city at a fixed time and prevents this, but this should VOR be the first game, especially in the new town of Bridgeport installed, because if the lags occur once they occur repeatedly , in retrospect, the Mod does not help unfortunately. But if it is installed before everything runs smoothly.
If you already had the problem and installed the mod in retrospect, just any cache folder in the Documents folder of Sims 3 delete, copy the game, create a new same folder to copy to the score and start the game again. Although one has to make his Eisntellungen new, but so can the lags behebn.