We have scripts for this:
Automating transfers or synchronization in parallel connections over SFTP/FTP protocol

I know this was answered many times, but could we please have a parallel transfer feature in scripting? Considering it's been frequently asked, it seems like there is demand for it.
It's a huge letdown that scripts can't perform on significant-size downloads (multiple large files).
We fully invested in trying WinSCP scripting, and we got all of it working, but it would be a shame to scrap it and re-do a higher maintenance alternative option.