Previewed at WWDC, launching in the fall.
2018 13-Inch MacBook Pro With Touch Bar Has Four Full-Speed Thunderbolt 3 Ports
2018 models ship with Intel's eighth-generation Core i5 or Core i7 processors, which both support up to 16 PCI Express lanes, providing enough bandwidth for maximum data transfer speeds up to 40Gb/s on all four Thunderbolt 3 ports.
2016 and 2017 models of the 13-inch MacBook Pro with Touch Bar could be configured with sixth- and seventh-generation Intel Core i5 and Core i7 processors, which supported up to 12 PCI Express lanes, limiting full speeds to the two left-side Thunderbolt 3 ports, with reduced bandwidth on the right-side ports.
Now, users have the freedom to plug higher-performance peripherals into any Thunderbolt 3 port they desire without compromise.
All three generations of the 15-inch MacBook Pro with Touch Bar have always had four full-speed Thunderbolt 3 ports, while the 13-inch MacBook Pro with function keys has only two Thunderbolt 3 ports, both full speed.