ID 356210 - Node graph performance issues when working with large number of Python-based parameter expressions

Problem summary

When using large shading networks with a large number of Python-based parameter expressions, users are experiencing slowdowns when creating GafferThree nodes or when creating lights in GafferThree nodes.

Customer reported version:
katana.2.6v4

Customer reported platform:
centos7

Steps to reproduce:

1. Download and open the attached Project.

2. At the end of your large shading network, create a GafferThree node

Result:

The creation of the node is extremely slow, due to the shading network calculations.

Possible Workarounds

• Replace Python-based parameter expressions with reference expressions where possible.
• Optimising the shading network to be smaller, and contain less expression heavy nodes.
• Optimising in ways such as creating a SuperTool to replace multiple group systems to drive the Node count down.
• Look file baking parts of the scenes and reading them in later down the line.
• Reduce the number of Python-based parameter expressions where possible.

Reproduced by support:

• Katana3.0v1
• Katana2.6v4

Expected behaviour:
GafferThree and other nodes should not take a long time to build in the scene

Actual behaviour:
It takes a long time to create a new node (especially complex SuperTool nodes like GafferThree) or to add a light to a GafferThree node (which itself creates a number of nodes).