I am developing an XNA game for Windows Phone 7 and 8. The game is level-based. After finishing each level a screen comes up with a bit of stats summary. I wish to embed an ad in this screen, on which I expect users to only spend a few seconds on after each level.
Should persist instances of these ads throughout the game's operation and only make them visible on level completion? Or should I create new instances every time they are needed and destroy them once I don't want them anymore for each level?
My worry is that starting up an ad on a screen which is intermediate and lasts for a short while might not be enough time for an ad to download. On the other hand, having one or more ads running continuously in the background might not be a good thing for battery or performance.