Not sure if this is a bug so I'm starting a discussion instead. When displaying a Youtube feed, the page takes way more time to finish rendering completly than it takes when there are no Youtube feed entries. I've noticed a lot of "grey.gif" images are loaded when it does so (as seen by the "Network" tab on the browser's developer tools), maybe a fallback mechanism of some sort?
This seems to be the relevant part of the code loading the gif:
Lines 609 to 619 in fd7157e
There really seems to be a strange behaviour somewhere, because when I uncheck "Use lazy load mode to load pictures" in reading configuration and I go back on a Youtube feed, it loads quickly BUT there are so many requests going on after a little while initiated by youtube.com domain and others (doubleclick trying to load ads, etc) that it looks like every feed entry is entirely loaded as if I was clicking and opening every link at the same time.
I'm maybe not very clear in my explanation, please try by yourself with a Youtube RSS link and the developer tools