Explanation/Reference:
If the default configuration settings for running MapViewer are not adequate, you can configure MapViewer by editing the MapViewer configuration file, mapViewerConfig.xml, which is located in the
$ORACLE_HOME/lbs/mapviewer/web/WEB-INF/conf directory. To modify this file, you can use a text editor, or you can use the MapViewer Administration page.
Example:
Maximize tile generation throughput:
Increase the number of concurrent threads fetching tiles.

To do this, adjust MapViewer configuration parameter

concurrent_fetching_threads (default 4):
<map_tile_layer name="DEMO_MAP"

image_format="PNG" http_header_expires="168.0"
concurrent_fetching_threads="4">
...
</map_tile_layer>
References:
https://docs.oracle.com/cd/E17904_01/web.1111/e10145/vis_start.htm#JIMPV9487
http://download.oracle.com/otndocs/products/spatial/pdf/oow2010/spatialoow10_bestpractices.pdf, page
46