What makes Sketch render choking?

[Anonymous]

I run rendering yesterday and after 14 hours it's still...counting.
I guess it was ment to be quick alternative in presentation so it does not calculate:
- reflection
- refraction
- caustics
- radiosity
- global illumination
- any other fancy algorithm

It only draw edges and cast shadows from one light source (sun) so what is the problem here?
Don't get me wrong I'm not whining, I like it very much and use it a lot just want to know what to do to avoid insane rendering times. Is it about shadows, geometry, both? Any experience?

[Brad Elliott]

I use sketch and am pretty happy with it for quick & useful. But those Maxon Cinema 4D images were terrific. Hey, isn't Maxon owned by Nemetschek who just bought Graphisoft? Ah, a new dream to have. I look forward to it getting slowly ground to dust.

[Anonymous]

I turned to Max and Max+VRay sketch solutions.
Model: AC; Faces:18000; Render time: 80 sec; Photoshop postwork: 5 min.
Not bad at all!