A mobile wireless communications device is switchable between a plurality of wireless communications operating modes and may include an antenna, a wireless transceiver connected to the antenna, a first memory for storing a respective compressed file for each of the plurality of wireless communications operating modes, and a second memory having a faster access speed than the first memory. The device may further include a processor connected to the wireless transceiver, the first memory, and the second memory for copying the compressed files from the first memory to the second memory, uncompressing a selected one of the compressed files to generate and store a selected compressed file in the second memory, and processing the selected uncompressed file from the second memory and controlling the wireless transceiver based thereon.