Shader Thumbnail Generation extremely slow on first startup

[hendrik.weilerKEEA6]

In Maya 2025 we have a consistent issue with the Hypershade, node editor, and even the attribute editor when viewing a shader, being incredibly slow to work with when first opening a scene. The entire program freezes for up to 30 minutes while it slowly generates the thumbnails of the standardSurface nodes. During this process the program becomes entirely unresponsive, and the network traffic and cpu usage on the workstation spikes quite heavily, almost as if Arnold is rendering something. The resulting thumbnails also are mostly black so they are not even helpful in any way, and the mel flag "renderThumbnailUpdate false" does not seem to have any impact on this very annoying process (the program gets stuck for just as long, but instead of generating black thumbnails the thumbnails are just the Maya logo). This issue is consistent across multiple workstations, and all of our Artists are currently struggling with this. Is this a known issue and / or are there any ways to address this?
We are currently on Maya version 2025.3
and Mtoa version 5.5.5.1

[Stephen.Blair · Accepted solution]

Not a known issue. I couldn't find anything like that logged for swatch renders.

Did you disable Arnold Render Settings > System > Maya Integration > Enable Swatch Renders ?

Black swatches, even for a default standard surface node? Is there anything logged at all in the Output Window or Script History?

[lauri_barnhart]

Welcome, @hendrik.weilerKEEA6.

Just checking in to see if you saw the information provided by Stephen.Blair along with the outstanding question. Please provide an update here if assistance is still needed. If the information provided helped, please consider clicking on the 'Accept Solution' button.

Best,

[hendrik.weilerKEEA6]

Yes that did the trick!