I have this issue as well with folders with lots of files and or subdirectories. I'm not sure where a long time ends and a hang begins, but I just went and made a cup of coffee and the window which contains WinSCP is still just a blank white pane. I'm using version 4.04. It's faster to kill winSCP and login again than finish the coffee and get another cup while waiting for a refresh to finish. In fact on the directory I'm thinking of, I'm not sure if I've ever managed to wait it out to be honest.