Yup, signature guidelines. Sigs that are too big or have too many graphics slow the board down. Most of us probably have DSL or cable connections, but there are still people out there who are on dial-up.
Please keep banners to a width of about 500 pixels and a height of up to 200 pixels. If you don't know the size of the banner or graphic you want to use, right-click on it and select Properties from the menu.
The best size for an avatar is 100x100. Again, the check the size if you're unsure right-click and select Properties.
Animated sigs are fine and allowed, as long as they meet the size guidelines.
Even if your picture that you want in your signature is too big, there is a way to resize it. I know, because someone did that for me at LAF, for the signature I have now. It was pretty big at first. Unfortunately, I don't know how that resize that stuff.