Refractive Crystal render taking forever.

[Xntric]

This scene:


After 1 hours, it's not even done with initial render pass.
And for some reasons it's only shooting 36k Rays, whereas normally it shoots around 1.5/2 million rays when rendering.

My rendersettings in 1080p


The materials are nothing special
The crystals is just a refractive with some bump and dispersion. No caustics
The rock got some displacement to it, but nothing too heavy.

My hardware is fine, and it runs fine in other scenes.

[Xntric]

Found a solution.
https://forum.corona-renderer.com/index.php?topic=13958.0

Turns out if you have a lot of overlapping refractive geometry it goes really slow.

Turning on caustics fixed the problem and made it 20x faster.
They said that this has been fixed, but my problem occured in Corona version 3

[maru]

Actually, a very similar issue was fixed some time ago, so we will look into this once again.