Extremely long render time — 48h for one exterior image with water reflections

[Adrien_Cazorla]

Hello everyone,

I’m having a serious rendering issue with a large architectural visualization scene in V-Ray for SketchUp and I’m trying to understand what’s causing it.

A few days ago, this exact scene was rendering in roughly 2–5 hours per image. Since making some modifications, render times have become completely unreasonable.

The main changes were:

• Changing the Sun position/settings.

• Modifying the water material.

• Adding some vegetation and scatter elements (although nothing extreme).

At first, I thought it was just a heavier scene, but I launched a render at midnight and it was still rendering the next morning. I let it continue as a test, and after almost 48 hours it still wasn’t finished.

What makes me suspicious is that I noticed the render slows down dramatically around the reflections of the sun on the water surface. It looks like the renderer is spending an enormous amount of time resolving noise in those bright reflective areas.

Scene information:

• V-Ray for SketchUp

• Exterior scene

• Water surface with reflections

• Large amount of vegetation (V-Ray Scatter)

• No obvious error messages in the V-Ray log

• Previously rendered correctly in a few hours

Has anyone experienced something similar?
Could this be caused by:

• Caustics?

• Water material settings?

• Reflection/refraction depth?

• Sun angle creating difficult light paths?

• Something else entirely?

I’ve attached an image of the scene and would appreciate any advice on where to start troubleshooting.

Thanks!

[konstantin_chaos]

Hi Adrien_Cazorla,

This certainly doesn’t sound normal. Even 2 hours is too long in my opinion.

If you have a chance to share the project files (in a DM or a support ticket), that would be ideal. This will give us a chance to test and share more precise recommendations.

In the meantime you can try the following:

Disabling Caustics (if they are enabled) - both the global effect and the one in the material.

Disable displacement

Also try resetting the Render Settings using the button in the settings footer.

Regards,
Konstantin

[konstantin_chaos]

Here I did a quick test of a similar setup which rendered for 1min 27sec on my workstation - Ryzon 9950X.
Quality Medium + V-Ray Denoiser.

It slowed down a bit where the trees are stacked and the sun reflection on the water but wasn’t too bad.

[Adrien_Cazorla]

Hello! Thanks for ur answer ! I found the problem, it was because of my refraction water. I blocked it, and it worked perfectly ! I also disabled caustics and choosed Quality High intestad of High+ ! Thanks a lot for ur answer and the test !