Curl goez parallel
[W]e introduce the ability for the curl command line tool to do parallel transfers! Instead of doing all the provided URLs one by one and only start the next one once the previous has been completed, curl can now be told to do all of them, or at least many of them, at the same time!
Source: Curl goez parallel.
According to the article this feature is scheduled to ship in curl 7.66.0 on September 11, 2019.