On a completely new and different topic -
Grooms....
Seems, in a scene, Grooms cumulatively draw in memory as they are added into a scene, even if hidden.
So with 1-5, 6-10, 10-15, 15-20, etc, I start to see an increased 'general' slow down of the engine, even if I only have one groom visible on the CC3 avatar.
It's like just the fact that they are in the scene absorbs some memory-coins from the account.
Also, starting to see the pattern, if you have a loose generic groom, you can let it run wild.
But if it's a 'styled look' you modeled to the avatar, upping the stiffness helps it maintain its shape.
Which I can attest to is a good method because my own real-life hair goes beneath my ears half-way down to my neck and it moves same like a jello-jiggle when I vigorously shake it back and forth. It looks like UE4 hair jiggle.
So it a stiffer shape maintenance winds up a good approximate emulation of a styled hair.