Yeah those specs are a lot better than mine (i5 3570k, 16GB DDR3, GTX1060 6GB, Launchbox on a 5400rpm HDD, but with its cache on my samsung OS SSD, connected to a 4K HDR LG TV). So my guess would be caching at this point. Also what you can do is go to Tools/Options/Sidebar and check the box to show all in the sidebar, then select the All platform and see if you notice the caching bar, as that will cache images for all your systems in one go.