I have a very large set of polygons to display, and I cannot find a way to load them that is sufficiently fast and perfomant. I have tried GeoJSON, but loading is extremely slow.
I also just tested a large GeoJSON dataset on the new GeoJSONLayer that Rene mentioned. It works great, and is faster than a map service - GeoJSONLayer | ArcGIS API for JavaScript 4.14 .