Following the tutorial from saeedoo… which is an Unity adaption of the C# script /library described here, I created this TestGif. 1 GifImage per Frame and 320 × 240 px ~ 1MB
The text was blurry and the 3D-Text rendering behaviour has to be adjusted.
Unity Tutorial – Fix 3DText issues (Text rendered in front of Object + Blurry)
More (technical/internal) details can be found in the N2K database (Search for “Gif”)