Sir Pyke, you'll find that your plug-ins work a LOT better at that size as well. I've found that if you apply a plug-in to a small image you get a really strong effect, but it's hard to use for subtle touches, whereas when you use those same plug-ins on a larger image, it might barely be noticeable...then you just keep applying it until you've worked your way up the the effect you want without overpowering it.

For example, Sir Pyke, I applied a halftone dot filter to this same image, the one on the left at twice the size of the right.

Big difference.