From an electrical standpoint.
USB ports up to 2.0 deliver 5 volts at 0.5 Amps (2.5 Watts).
USB 3.0 ports deliver 5 volts and 0.9 Amps (4.5 Watts)
Samsung OEM charger is 5.2 volts and 2.4 Amps (12.5 Watts)
So a USB 2.0 port will be about 4 times as long to charge your S5. A USB 3.0 port...