Apple uploaded a new support document detailing information about connectivity and charging options for the MacBook Pro models. According to this document, the 13 inch MacBook Pro model with Touch Bar has reduced PCI Express bandwith on the two USB-C ports on the right side of the device.
http://www.notebookcheck.net/Apple-13-inch-MacBook-Pro-Ports-on-the-right-have-reduced-PCI-bandwith.181965.0.html