yes in this case
in case of adventure game with a lot of changing background and maybe moving it, a lot of sprite (ennemy and their animation), the player with his different animation .... creating that on start of lyout will lagg the game in start and make it unplayable ....
remember to preload sound and music , believe me that will optimize performance
iam testing all optimisation regarding all options and probability .... and i will post on forum "the final optimisation tips" specially for mobile phone (iphone 4 , galaxy s1) because these phone are not expensive and every person have at least these phone ... and specially because games are played by kids