Animations are totally unoptimized atm. I think we should use the following imagemagick options when creating animated gifs. -coalesce -fuzz 10% -layers OptimizePlus +map '
That will result in much more efficient thumbnails that are not 5 times bigger than the original due to all the extra color tables on each frame.
This likely requires separating thumbnail behavior for animated and non-animated renderings of GIFs.... will require a bit of experimentation.