I have used the new site designer to create 6 content showcase lines on my homepage (I love it :-) ). However, when I scroll down, they do take some time to load. I did some tests and my homepage takes anywhere from 22 to 38 seconds to load. www.sensual-x.com
The content seems to only load if and when I scroll down, instead of just downloading the entire page as soon as I open it (so scrolling would feel more smooth). So as I'm checking out showcase 1, the page should already be downloading showcase 2-6. So if I then scroll to the next line, it's already there, instead of still having to load.
Maybe caching might help?