Setting transform.hierarchyCapacity through code doesn't work

Hello, I am trying to prepopulate the transform memory buffer before streaming in objects. At build time, I store a list of the transforms in my streamable prefabs and then try to add that to the transform.hierarchyCapacity of the object that I am parenting the streamed object to

Code (CSharp):

1.  
2. Debug.Log("Before prealloc in " + thisRoom.name + ", " + transform.hierarchyCapacity);
3. transform.hierarchyCapacity += data.additionalHierarchyCapacityToAllocate;
4. Debug.Log("After prealloc in " + thisRoom.name + ", " + transform.hierarchyCapacity);
5. _instantiatedPrecombine = Instantiate(_loadedPrecombine, transform, false);
6. Debug.Log("After instantiating in " + thisRoom.name + ", " + transform.hierarchyCapacity);

However, the hierarchy capacity does not increase until after the instantiation, or at least it doesn't appear this way in the log statements. Any ideas? Unity docs on this method are sparse

 

Are you doing this because you actually have a performance or memory problem, or is this just speculative optimization? If the latter, I recommend just adding all the children and letting the transform grow as usual.

 

It's speculative, but bc it's a simple optimization I figured what's the harm
The prefabs are pretty complex, can contain around 350 children

You do have a point regarding actually profiling this, but because it is such an easy thing to do, I figured it would be worth adding - even if it's not, it would be good to know the reason why it isn't working for anyone else who stumbles across this thread