Hi Janne, is it possible for you to zip up your 20MB file and share it with me at moi@moi3d.com with some file sharing service like DropBox, SkyDrive, etc... so I can test with it over here and see what might be going on?

Usually you should only see pretty considerably large files taking that amount of time to open.

Have you recently installed a new virus checker program by any chance?

- Michael