SFTP Speed - slows down...

[flme]

Hi there
I´m making a program, that downloads a lot of files from a SFTP server to local harddisk, and the files varies from very small (few bytes) to very large files (6 - 7 gb - or even larger).. My problem is, that the download slows down during the download. From starting with 1 - 1,5Mb/s, the speed slows down do a few hundred kb/s. It can be different from download- to download, where in the process, the speed slows down, but in large files (over 200Gb), it usually are "visible".. If I switch to usual FTP, the download progresses as expected.. If I test download in an other program (fx. SFTP download via FileZilla), the download progresses as expected..
Why this behaviour ?? Is there some "buffers" that needs to be read/emptied along the download, or what ??

Kind regards

Flemming M...

[ViktorV]

Please specify your exact version of SFTP server. Also clarify whether performance loss occurs when downloading only one file of large size.