Speed of copying files

Hi,
i´m using C# with the WinSCP.dll. If i copy 5 files with my application in C#, this will take 9 minutes. But if i use the WinSCP-Program it will take 2 minutes. I have debugged the program, but the session.GetFiles(remotePath, localPath).Check(); need the most time. Is that normal?

My second question is, what does the .Check()? I found noch documentation about this.

Thanks for your help.

Please attach a full session log file both from WinSCP application and the .NET assembly showing transfer of the same file.

Regarding .Check: See https://winscp.net/eng/docs/library_session#results