In December 2015, Nintendo filed a patent for a game console with a 'supplemental computing device,' this patent has been officially granted via an Issue Notification (NeoGaf) which lends credence to the leaks for the NX.
Previous leaks suggested that the NX would be a two-part console: one handheld portion and one home docking system connected to your television. This patent essentially details the home structure that is plugged into the television and its supplemental computing device.
According to the patent, the supplemental device will be "configured to detachably couple to a game console in order to provide processing resources for an increase of speed or quality of a user's gaming experience." This basically means that the supplemental device, in addition to the home device, will work to boost performance.
The patent doesn't say, but it's possible that this supplemental device will be used to boost the performance of the handheld portion of the NX.
Of course, there's always a chance that this patent will lead to absolutely nothing, it's just a patent, after all.
¯_(ツ)_/¯
