I am an encountering an odd issue in Unity 6.002 where if I have a handful of CC models in a scene, and roughly another 30 textured meshes, memory allocation will climb until it crashes the engine completely. I have tested this in isolation in a bare scene with many different meshes.
Example case (not actual numbers):
If I have the following - memory will increases incrementally based on each mesh, as expected.
10 meshes of object A
10 meshes of object B
5 character creator characters.
If I add even just one more CC character, then memory allocation will increase until the cap hits and Unity crashes. This ONLY happens when I have Character Creator characters within a scene. I can only assume there is a shader issue, but I am unable to isolate it that granularly.
This is replicable reliably in empty projects.
Something interesting - game base characters are not resulting in the same issue, even if I have more tris in the scene (because I duplicated many many more as a stress test) than total tris from the non-game base character. 
Sounds like you’re running out of VRam.
Full CC3+ characters use a lot of textures, and they have a lot of blendshapes for the expressions. Unity does all blendshape combining on the GPU so it all adds up.
GameBase generally has less polygons, fewer blendshapes for the expressions and lower sized textures.
Realistically you should only use full characters in a scene for extreme close up’s / cinematics. For general use those characters should be GameBase, actorbuild versions, low poly lods, with strict texture size control.
You can try rebuilding the materials using a lower texture size option. See if that lets you put more in the scene.
I may have spoke too soon…
Converting to a game base worked for one character, but not the second one (which uses very different textures). Even as a game base with basic materials, the issue occurring.
I’m testing with just 12 Game Base models with Basic Materials and no features, and we are again allocating the remainder of available memory (anywhere from 8-12 gb),
So, the project scene will jump from 1.5 GB until about 10 GB. I don’t think this is a polycount issue at this point?
Update 2:
Converting to Game Base is working for any character that wasn’t generated with Headshot.
Final Update: I’m not crazy
Unity confirmed that it is a bug and they are working on a fix. I have no idea what the issue was, but wanted to share in case anyone else is encountering the same issue right now.
