The getSamples method in ArcGIS Server Image Service can be used for measuring performance.
Enter geometry.
{"x":-19837193.917600676,"y":-3812345.7636769526,"spatialReference":{"wkid":102100,"latestWkid":3857}}
Enter Mosaic Rule.
{"mosaicMethod":"esriMosaicCenter","sortField":"","ascending":true,"mosaicOperation":"MT_FIRST","multidimensionalDefinition":[{"variableName":"ALL_SFC_SW_DIR","dimensionName":"StdZ","values":[0],"isSlice":true}]}
Enter pixel size.
{"x":611.4962262813791,"y":611.49622628138,"spatialReference":{"wkid":102100,"latestWkid":3857}}