I have an iPhone 4s, and most games load pretty quick. In addition, most games load instantly once they are in memory (ie one of my last 4 or so apps loaded). In contrast, with Dragonvale I get a load screen almost every time I lock my phone, or switch apps. Does anyone else have this problem? Is it just expected, or is there a way to reduce/eliminate it? If relevant, I am still running iOS 5.0.1.
Dragonvale used to have major load-time issues, so make sure you're on the latest version. It used to load the game twice, and it reloaded every time another app opened. I don't think iOS 5.1 is required for the latest updates, but I'd still recommend it.
However, it sounds like your specific problem is because "loading" Dragonvale actually happens from their servers; it's thus dependent on your internet connection speed. Slow internet will cause slow Dragonvale loading.
Playing it at home on WiFi is probably the best way to make sure the game loads quickly, but it still depends on your internet speed.