The port your device is designed to plug into makes all of the difference in the world when it comes to download times. Serial ports Serial ports are mainly used to connect analog modems so you can connect to the Web. However, many digital cameras use them to transfer image files to the computer. There isn't a slower port on the computer. Parallel ports Parallel ports are normally used for printers and some types of external storage devices.
Many card readers plug into the parallel port.
If you add a card reader, be sure it has a passthrough connector so you can plug the reader into the computer's only parallel port and then plug your printer into it. If it doesn't have this capability, you have to keep swapping cables. A big advantage of this type of port is that many devices can be connected to the same port. One device is plugged into the port and then another device is plugged into the first device. SCSI ports are fast but on PCs you need a SCSI card and the various settings can be difficult.