Users cannot specify themselves if they do not want to view GIFs or not. http://www.everypony.com/forums/profile.php?do=editoptions#cb_showsignatures There is an image size limit that can be specified for sigs, but unfortunately it only applies to images uploaded to vB (attachments feature). It does not apply to using IMG tags, as they have no limit. :I
:/ I'm sorry, but there has to be a way... I might not be the best coder, but i do know that there is a way to restrict IMG Tags. I've seen it done. I have done it with HTML, but still. Unless you don't know how to code with vBulletin, it should be possible. (i'm not calling you dumb or inferior, or anything pointing that you can't do a job)
A possible solution would be to create a custom BBCode that is identical to IMG but does not display GIFs, and then disallow images in sigs. Then again, that requires actual work to solve an issue.
I don't think you understood. Of course IMG tags can be restricted in sigs, but I'm pretty sure that's how 95% of users insert images though. People are just gonna whine and cry that they can't use IMG tags anymore. But yes, IMG tags can be blocked. GIFs can just be disabled in sigs without the need of a custom BBcode. But I'm sure most users wouldn't be happy with that. Personally, I think it's best that you go to your profile options and disable sigs if they bug you that much. Simple. They aren't in your way making you lag, and the user doesn't need to feel bad and remove them. Nobody dies in a fiery explosion. The end.