Methods performed by a serial flash memory and a memory controller in a performance-enhanced mode

Methods for enhancing performance of a serial flash memory in a performance-enhanced mode are proposed. The serial flash memory is connected to a memory controller through at least a serial clock (SCK) line, a serial chip select (SCS) line, and a plurality of serial input/output (SIO) lines. In one embodiment, the serial flash memory first counts an enabled duration during which the SCS line is continuously maintained at an enabled state. If the enabled duration is longer than a threshold number of cycles of a clock signal on the SCK line, the serial flash memory regards information received from the memory controller through the SIO lines during the enabled duration as a command-omitted read instruction. Otherwise, the serial flash memory regards information received from the memory controller through the SIO lines during the enabled duration as a non-read instruction.