Generating the screenshot was slow but didn't take anywhere near a few minutes for me. Maybe ~5 seconds. Site probably getting a lot of traffic, I got some errors at first but it works fine now.
Cool site.
Cool site.
As suggested in another reply, linking via iframe would still be a nice option to have when submitting.
Screenshot + link to open in a new window actually started as a sort of a workaround but I think this allows people to focus more on first impressions instead of going into usability testing.