Can be patched to work much better, if you are invested in an ssh-based workflow
Common tools in this category are single-threaded
Versus support for parallel transfers
GridFTP (including Globus GridFTP)
Breaks files into small pieces, transfers many pieces concurrently, and reassembles them at the receiving end
Tends to get better performance out of networks with symptoms.
May not tend to get better performance out of transfer paths with other problems
Authentication and licensing might present obstacles to use in ad-hoc workflows
Lftp
Very versatile (Russian origin) program with features such as mirroring and parallel transfers
Key Points
SFTP, although common, is not the best application for moving data and there exists other SSH versions and tools that are better to transfer large data.