Try clearing your Multitasking bar if you haven't already. To do that, double-tap the Home button. It should show up at the bottom of your screen. Press and hold one of the apps in the Multitasking bar, and you should get the option to delete the apps. Doing that officially closes the apps (even when you go back the the home screen, the apps are still open). It helps to make everything to run faster, and it's good to do it as often as possible (maybe once a day or so).