j0schi - The more objects you create and spawn, the more the cpu is used. Take an infinite runner game for example, particularly temple run. There is an infinite board and there are a serious of 10 or so coins to collect in spurts the entire way. If you were to create the random board (which is needed in that type of game) and create new coins after each one is collected (my ex-boyfriend's daughter hit over a million coins collected and she's only 8) that would use well over 50% of the cpu. At the very least and that's far more taxing than any program should be.
But...if you just move the same 10 coins or 20 coins as they are being collected, the player will never notice the move and it'll save the fps and cpu.
Kyatric offers this link in ddaan9 's post about spawning vs. visibility
Then again...if you're only creating a couple objects and you never destroy them , your cpu and fps rate probably won't even budge.