I've noticed recently that large image files (bigger than 1.5 MB or so) have a significant tendency to fail to load, giving the classic "broken image" icon. Spam-refreshing the page or selecting "load image" in the context menu can make things work, but the bigger the file, the less effective (more tries are required for a successful load). Some really large (>8 MB or so) ones just flat out refuse to load, no matter how many times they're refreshed. Seems to be insensitive to file types, and larger animated GIFs will also cause the same problem as PNGs or JPGs. Opening the images in a new tab results in a partially-rendered image (visible top fraction, and then the rest is just gray), and GIFs will play a while and then freeze. I'm using the latest version of Chrome on a reasonably modern PC with ample RAM and a decent internet connection, and I've tried clearing cache/cookies and disabling all active extensions, with no effect. It seems to be constrained to e6 - No issues with other imageboards or the web in general.
I realize that this is probably just a server demand issue and there's nothing to be done, but I figured I would still throw this up here for the sake of documentation, if nothing else.