Ok, this is pretty darn cool.
A group of enthusiasts have found they were able to boost the video performance of the Radeon Pro 450 found on the 2016 15-inch MacBook Pro by nearly 400 percent via external GPU attachments.
External GPU enthusiast site egpu.io has affixed a GTX 1080 Ti to an AKiTiO Note and Mantiz Venus enclosure. While the cards may be hamstrung slightly by the Thunderbolt 3 interface not being as fast as a 16x PCI-E slot, the results are nonetheless impressive.
In a best-case scenario utilizing benchmarks, the 15-inch MacBook Pro with Radeon Pro 450 scores 5822 via the Luxmark 3.1 benchmarking software, with the Radeon Pro 460 scoring 6056.