Final Render

Output
Normalized z-buffer
Sample count

Render time 0:02:48. Adaptive 8-64 samples per pixel. Mitchell-Netravali Reconstruction filtering. Halton 2,7 for AA. Halton 5,3 in circular coordinates with inverse CPD for DoF. Glossy reflections and refractions with uniform-random ejection sampling for normal shift. 8 shadow rays for point lights, uniform-random rejection sampling.

Bug 1 -- Unnormalized shifted normal

Output
Normalized z-buffer
Sample count

Render time 0:01:04. Here, I did not normalize the normal vector after shifting it (no soft shadows here).

Machine Specs

Processor	1.4 GHz Intel Core i5
RAM	4 GB 1600 MHz DDR3
Graphics	Intel HD Graphics 5000 1536 MB
Software	Xcode 9.0 on macOS Sierra 10.12.6