This is ... legitimately insane. Why on earth do you need more than 50 for a 2d portrait?could this be set to 100 or 1000 next patch? I like to go all out with bones when animating/rigging.
Modern 3d, cinematic quality, real-time characters barely go over 800 bones. There is no reason you need to for portraits.
Have you tried finessing the skinning of your mesh to the skeleton rather than adding more bones?