Actually mind, I was watching the network tab on refreshes before and after I cleared all my browser caches and it still went through downloading every single image in a .45ms to .67 ms when refreshing after. And the time from when the page loaded to the throbber disappearing was about 2.5 seconds in either case. Safari and Chrome similar result on aforementioned 8-9 year old high spec mac. Maybe it's me though.
I didn't even want the feature when I wandered into the thread, lol