To make the game run as smoothly as possible, please close all other apps you have running in the background. If you are still having problems, putting the phone in airplane mode can improve performance. However, some modes are not available offline. You can also try to delete and reinstall the game. If you log in to the online section of the game with Facebook/Twitter/Google+/GameCenter, then all of your progress is saved on our servers and will restore as soon as you log in again. If these steps don't help, you can try to reset your phone or tablet to factory defaults in the settings. Remember to do a backup before you do this, or you will lose all your photos and contacts on the device.