For those of you unaware, GIFs are a terrible format for doing what most people do with them. They were originally designed for small, pixelated, very short animations. People use them for small movies, now. They have a terribly limited number of colors, unnecessarily large file sizes, take forever to load, etc. Fortunately, there is already a solution. Sites like Gfycat and Imgur already convert the gifs into little muted looping HTML5 videos, and that's the default when you share them. They're a 20th the file size with better colors with less lag, but are otherwise identical. Sadly, although they have become immensely popular (without people knowing it) they don't work on this site, you can't embed them. What would be great is to be able to do that. I wouldn't think it would be that hard, they are just small HTML5 videos, which YouTube uses already. I would even be fine with having to use the video embed to add them. It would just be a simple way to make sharing GIFs more convenient (since you have to use a non-default option to share them here now) and help reduce lag a bit on threads with lots of GIFs.
I imagine this will come down to the Xenforo being old and hacked together making any kind of additional features like this break. There has been talk of updating for a very long time and nothing has ever happened about it.