When Android devices are left idle for a period of time, the devices go into sleep mode. When they are left for an extended period of time, between 75 and 90 minutes, the devices go into deep sleep.
When the device is subsequently revived after being in deep sleep, an instantiated sencha mobile app is extremely slow to respond to input. It seems as though the app is locked up, however if enough time is allowed to elapse, the app begins to respond. Depending on the device, the required time to elapse before the app begins to respond is between one to two minutes.
This behavior is not an issue if the devices have gone into sleep for a short period of time.