When you post screenshots in spoilers, resize them so they fit within the forum width. 720 is about the width of a spoiler tag. It's not that hard, we're all working with photoshop, gimp, or paint.net... or paintshop pro.
Unless it is required to be huge, I'm tired of seeing stuff like this
which by the way, is an awesome wallpaper I randomly googled cause it's huge.
Edit: Oh, I forgot to mention: turn them into jpegs too. Even high quality jpegs load forever faster than a png. Where forever is usually about four times or so.