Lag copying files from SFTP site to network share

We have a daily task where an engineer needs to connect to an SFTP site and copy down daily files out to a network share on the corporate network.

When they select the files and drag them over to the share location it can lag up to 3-5 minutes before the Copy dialog box opens asking what to do.

if we change the location to the local system HD the copy window open immediately.

Has anyone else had this behavior?

Additional information, if we reboot the server this doesn't lag, the appearance of lag comes after several days of being logged in and transferring files.

Thanks

Thanks for your report.
I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.