S3Express supports multithreaded operations to upload and query multiple S3 items concurrently. This can speed up S3 operations considerably. Multithreading helps speed things as you can make full use of all the available bandwidth, especially when uploading, deleting or listing a large amount of files that are relatively small.
The number of concurrent threads to be used by S3Express during deleting, listing or querying of S3 objects can be set using the option -qmaxthreads : www.s3express.com/help/vv_options.html