Quite a fun game that made you think about shop placement, but in some of the later levels you could just bunch shops in one area leaving the rest of the map relatively untouched.
1) Quality option. Even in "fast mode" the game would slow right down when too many customers were on the screen.
2) Freeplay mode. Either for practice or unlocked after completing the final level. No goals or time limits to see what you can build.
3) Distraction variation. Customers spend different amounts of time at newspaper stands, icecream etc so they don't always leave in the order they arrived.