Hitting enter searches for me. It shows results instantaneously. It says clearly at the top in big letters "7,636 results for cat" so you know that you can pretty much hit "show more" endlessly. Which instantly loads. And when I click on something yes there is a 2nd scrollbar (not 3) but it's only for the "object details" sidebar... it doesn't apply to the main page viewer part. And the back button works perfectly.
Honestly it sounds like you just have a terrible network connection maybe, or they had temporary traffic congestion? Or what browser are you using... perhaps it's one they haven't tested against? (I'm using Chrome on a MacBook.)