On top of default 3d model importing, compresses all embedded texture into S3TC (DXT1, DXT5) format to save disk space.
By default, Godot 3 imports 3d models' textures with uncompressed fomat (RGBA8), which results in unreasonable large file space.
- In Godot Editor, go to Project > Project Settings > Import Defaults
- For Importer, select "Scene"
- Set "Custom Script" to the path to gd_3d_import_script
- Now every 3d model you import will have their texture compressed