Here we are, talking of renderers, performance and realism as usual.
On BlenderNews.org you can read an article by Olivier Boscournu in which three free render engines are compared.
Olivier renders the same scene by first using the old but well-performing Blender internal engine, then using Yafaray 0.1.2 and finally the brand new and still young Cycles. The results are clearly quite different both from the realism that from rendering time. Olvier does its own analysis by going to review the different engines under different aspects and so bringing to light what are the pros and cons of each of those.
Unfortunately, he tested only three of the rendering engines we can use with Blender. It would be useful to repeat the same feel by introducing other engines as Kerkythea, v-ray and Octane renderer.
However thanks to Olivier for his very useful analysis.