Have you tried the same out side IICS say do SFTP command from secure agent ,to see how is the performance outside as there would be multiple parameters in it.For archive you need have post scripts to handle it ,once jobs completes You can use File Processor Connector to archive and un-archive local files
1> we have to check logs and see what is taking time.
2> moving/archiving is possible through another task, not within the same task
3> no i think, it always works as file watch only.
I will check the log, but moving/archiving files within SFTP possible without custom commands? And we are connecting sftp thru public private key authentication. So i don't see option sshkeyfilepath for file move operation.