I have two levels with background images each at 3066 x 767 pixels, plus
a smaller Title and End background, all png files(thats all image types available at the moment).On my server it takes 45 seconds for a new load. Loading Construct 2's Space game it takes 35 seconds to load, new start.
I don't know whether this is exceptable or not in gaming circles.
If I could have used jpg files, I would have cut the background file sizes by two thirds, hoping for this file type soon.