WOW MY GODS, Add cover art edits are displaying 500×500px thumbnails in a 250×250px sized box (it seems to be the case of all types of CAA edits BTW).

Those thumb500.jpg are usually three times bigger (in octets) than the thumb250.jpg that we should be using.
By using the thumb250.jpg (remember that we display them in a square 250 box anyway) we could improve edit search loading times and bandwidth usage greatly (and it is heavily needed).

☞ Without saying that, moreover being useless, displaying a client resized picture is usually uglier than displaying genuine size (be it server resized).