Your raster data source does not have statistics computed, which can degrade your raster display and potentially impact drawing performance.
Solution
Check the drawing performance and appearance of your layer, or basemap layer, in ArcMap. If you see the need to make changes, calculate raster dataset statistics to improve your raster layer display and increase drawing performance for your raster data source.
If you are publishing a map service you can check the drawing performance in the Preview window.
More information
Statistics are required for a raster dataset to calculate its display, such as applying a contrast stretch or classifying data. If the statistics do not already exist for your dataset, they will be computed at the time the map is rendered, which can obviously affect performance. Compute them ahead of time, and you can significantly improve performance.
See the Calculate Statistics geoprocessing tool for more information on how to perform this operation.