Load cached map tiles from ArcGIS Server

For some reason it seems that VSW is not making use of Cached map services.

Map Services with a cache load dramatically faster in the ESRI Map viewer than VSW. My best suspicion as to why is that when looking at the network activity in the browser, the ArcGIS MapViewer is requesting map tiles while VSW is requesting a single image with bounds for the current screen.  

Seems very odd that the same map loads dramatically faster in Portal than VSW.