A factory reset can often fix many types of software performance issues such as battery life issues, freezing, overheating and other software glitches.
The following link contains instructions on how to perform a factory reset. Please note that this will erase any user data currently stored on the device, so we suggest backing up any crucial data before performing these steps: http://support.apple.com/kb/ht1414
Please ensure that you are restoring to factory settings, and not reverting to a backup.
If you continue to have any issues, please feel free to contact our Support Team for further assistance.