iPhone is Slow – Use Task Manager to Close Background Apps
Your iPhone is slowing down. It takes several seconds to switch between apps. Your battery seems to be draining quickly.
Close all of the background apps. They stay open even after you restart the phone.
Simply Double-click the Home button on your phone.
This brings up a window at the bottom with all of your open apps. You can scroll sideways to see them all.
Hold your finger down on any of the icons for a few seconds and they will all appear with a red symbol that will allow you to start closing them.
Tap on all of the apps to close them and then press the Home button again to go back to the home screen. You will notice a great performance gain.