Slow SFTP transfer

I have a scheduled process that transfers a large file to a Solarwinds SFTP server.  I have done some tests and determined that I am getting about 80MB per second if I do a file transfer over SMB (just copy/paste using windows file explorer to the UNC path).

I am getting only about 4MB per second over SFTP using Filezilla as my client.  Same source file, same destination as the above example, that way I can rule out disk based transfer speed issues.  It makes SOME sense that I would take a performance hit over SFTP but this is a HUGE performance hit.

Any ideas?

THANKS!

--Dan