ID 407010 - Scene Graph tab is slow to resize header columns when many locations are expanded

Problem summary
Once a larger amount of items have been expanded in the Scene Graph, resizing the header columns becomes laggy. 

Customer reported version
Katana 3.1v5

Customer reported platform
Unknown.

Steps to reproduce
1) Create an Alembic_In node.

2) Set the abcAsset parameter to a large alembic scene file. (for example, use the attached file)

3) Set the view flag on the Alembic_In node.

4) In the Scene Graph, right-click the "root" location and click "Expand All".

5) Resize the "Name" header column.

Expected behaviour
The header column scales without any noticeable delay

Actual behaviour
The Scene Graph tab will freeze while the header column is being resized.
This issue occurs even when all the items in the scene graph have been collapsed.

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:

Katana 3.2v1 - Windows 7, CentOS 7
Katana 3.1v5 - Windows 7
Katana 3.1v1 - Windows 7
Katana 3.0v1 - Windows 7
Katana 2.5v1 - Windows 7, CentOS 7 

Katana 2.1v6 - CentOS 7
Katana 2.1v5 - CentOS 7
Katana 2.1v4 - CentOS 7
Katana 2.1v3 - CentOS 7
Katana 2.1v2 - CentOS 7 

Unable to reproduce bug in:

Katana 2.1v1 - CentOS 7
Katana 2.0v1 - CentOS 7
Katana 1.6v3 - CentOS 7 

Earliest version tested

Katana 1.6v3 - CentOS 7 
- This issue doesn't appear in this version and has regressed