That's not what I meant. Having to load a large image for every post is just a stress on bandwidth.
Some of the other sites I've visited usually impose guidelines so the forums don't lag or become cluttered. It works out pretty well.
I think 300 x 90 pixels is a good standard for sigs. If DJP would strictly enforce a resolution (and size limitation) like this, then the forums would load much more efficiently.
And Bummerdude, your work is awesome.