I don’t know if this applies to you, but don’t use the compression flag (-z) for files that already is compressed (like video). The transfer will get CPU bound quickly if you have a fast internet connection.

I went from 13 Mbytes/s to 200 by removing the -z flag, and the compression ratio was non-existant anyway.

Good thing this doesn’t make them more prone to taking bribes…

Seems like a solution in search of a problem.