Not responding TGP3

[mogn]

I load attached tgc. After the preview has finished, I add a displacement shader.
After the preview has finished, I assign the node named spire to the displacement function.
Then tgp3 stops responding. It is not a memory problem.
 

[JimB]

Try pausing the preview the render, then;
Unplug the displacement function.
Assign the spire node to the displacement function.
Plug the displacement function back in to where it was.
Unpause the preview render.

Does that stop everything from hanging?

[mogn]

Assign the spire node to the unplugged displacement node (preview paused) works, the minidisplay shows the expected landscape.
Connecting the displacement node to the compute node, seems not to finish (the connection line stays green)
Unpause enters not responding mode!

The reaction is the same in TGP2.

If I replace the spire node with 8 nodes in the group it helps. But TGP3 reacts extremly slow.