Feedback Sprite.Create slow

I am my own custom sprite sheet importer, it loads data exported from TexturePacker. All this works fine, but it seems that creating a sprite that I will always overwrite with my own vertices and uvs is extremely slow.

I assume that it's trying to generate tight packing, which I do not need the result of. So it's wasted work. Can we have an API that allows us to create a sprite with our own vertices and UVs in one go.