Hello,

I noticed an issue with Ramp nodes in material libraries (in Karma and Arnold) and wanted to check if anyone else noticed the same before I create an RFE.

Any ramp node, in my example I use float, is extremely slow and laggy when the Hydra viewport (scene view) or the stage graph is visible. It does not matter whether the node is even plugged in, meaning it's not even in the stage.

As soon as you remove the Scene View tab or pause it, the lag stops and I can move the handles around really fast. Another workaround is to set the evaluation to manual, and switch back to Auto Update once I'm done adjusting the ramp.

I noticed it mostly in H20.5 but still sometimes happens in H21.

Has anyone else noticed this and has more insight?

Try putting the material library down at the bottom of the LOP network. It could be that there is a lot of scene/tree reevaluation being recooked further down whenever you change things in the material.
Just a thought.