It was just a suggestion. It may be time for you to seek out a different wallpaper or maybe one like it with lower resolution.
This wallpaper is a high resolution, hence the big file size. A plain black wallpaper of the same pixel ration is going to be half the file size. So it may be that other wallpapers you are using don't have as many color variations which is why you don't see that affect upon them. It very well still could be a OS related issue as I pointed out before it has happened in the past. Otherwise, I would just stick to low res (less colors) wallpapers if you don't want to try a new OS.
Originally Posted by Jash
Good luck. Let us know what happens.