VideoCardz crunched the numbers and notes the Radeon RX 590 is about 12 to 24 percent faster than the Radeon RX 480 - making it a bigger jump in performance than the Radeon RX 580.
Based on these results, the new offering will put a lot of pressure on NVIDIA's GeForce GTX 1060. This is likely the reason why NVIDIA is working on a GDDR5X variant of the GTX 1060.