Hello Eric Kriener,
There could be multiple reasons why it takes 20-30 seconds to return an image. If possible I would recommend making the request from REST on the ArcGIS Server machine. This would eliminate any network latency between client and server.
How To: Execute a Export Web Map task operation from the REST endpoint
Another main factor in this process is the location of the service source data in relation to ArcGIS Server. What is the data source for the map service (e.g. reference, copied, file geodatabase, enterprise geodatabase)? Is the map service cached or dynamic?
Thanks,
Thomas.
