My passport is USB 3.0 drive in order to utilize the full speed of the drive you need to make sure the drive is connected to USB 3.0 port.
Also, the speed mentioned in the user manual of USB 3.0 supports interface transfer rates ‘UP TO’ 5 Gb/s.
USB 3.0 is backward compatible with USB 2.0. USB 2.0 supports interface transfer rates ‘UP TO’ 480 Mb/s.
Speed of the file transfer to the drive also depends on the following points mentioned in the below link.
https://support.wdc.com/knowledgebase/answer.aspx?ID=17243 (Please refer to Client System (Computer) )