Do you already use Image.BuildOverviews? It should be available in version 4.8.8.
More complicated option is to generate tiles from images: http://www.klokan.cz/projects/gdal2tiles/ (or gdal2tiles Python script), add them to MapWinGIS tile cache and add a custom tile provider.
More complicated option is to generate tiles from images: http://www.klokan.cz/projects/gdal2tiles/ (or gdal2tiles Python script), add them to MapWinGIS tile cache and add a custom tile provider.