Following the remark of Mike53 , here is a comparative rendering of his project.

Common settings:
- antiAliasing.min = antiAliasing.max = 1, samplerAlgorithm = bucket, shininessShader = silk, diffusedBounces = 1
- Enhance external brightness option checked

globalIllumination = default (rendering time: 35min)


globalIllumination = path (rendering time: 2h 21min)