ImageryLayer performance with external service

[EricDurbin]

I'm using an imageryLayer with an external service in 4.21. There is a slight delay upon initial load, pan, and zoom within the map while it is calling exportImage and is processing on the server side. Is there anything I can do to improve the performance or perceived performance upon the initial or subsequent requests?

let mosaicRule = new MosaicRule({
    lockRasterIds: this.objectId,
    method: "lock-raster"
});

let rasterFunction = new RasterFunction({
    functionName: "Natural Color with DRA",
    pixelType: "U8"
});

let layer = new ImageryLayer({
id: "rgbImageryLayer",
 url: this.serviceUrl,
 mosaicRule: mosaicRule,
 noData: 0,
 renderingRule: rasterFunction,
 format: "jpgpng" 
});

map.layers.add(layer, 0);

https://landsat2.arcgis.com/arcgis/rest/services/Landsat8_Views/ImageServer/exportImage?f=image&bbox...