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.