Outside of a GeoCities or Tumblr page that's made up of an obsessive amount of GIF posts, they are already small in size, audio-free, easily embeddable and non-CPU intensive.
I can't imagine what's more basic in an image-sequence format than a series of JPEGs rapidly playing in succession of each other.
it's not small in size. take any 30 frame moderate sized gif and you'll see a 2-5mb download.