A high-performance data storage device is disclosed. A controller updates a sub mapping table on the temporary storage in response to a write command of the non-volatile memory issued by a host. The mapping sub-table corresponds to a logical group involved in the write command and is downloaded from the non-volatile memory. When the mapping sub-table has not been completely downloaded to the temporary storage memory, the controller pushes the write command to a waiting queue to avoid dragging the performance of the data storage device.