The option for copy_data_from_server should be checked only when the ArcGIS Server account cannot be granted access to the target_cache_path. When this option is used, cache tiles are first copied to the ArcGIS output directory and downloaded to the target_cache_path on the client. Using DO_NOT_COPY will move cache tiles from the service cache directory to the target_cache_path, which will be faster but requires that the ArcGIS Server account has write permissions to target_cache_path.
Grant write permissions to the ArcGIS Server account at the target_cache_path to gain better performance. Uncheck the option to copy_data_from_server in the tool. In Python, set the value of copy_data_from_server to DO_NOT_COPY.