We used to be able to remove entity shadows with a file called shadows.material, but that file relied on the old render engine and does not work on RenderDragon. I have no clue how to do this on the newer versions, and would love help figuring out how to do this.
The main reasons I want to figure this out is to improve the performance of a friends realm. We got tooooo many mobs around, so I figured that removing the mobs shadows would greatly decrease the amount of resources being used to render the mobs.