In 2011 I did free render engines comparison – NOX, Luxrender, Cycles, Mitsuba, Yafaray. Cycles seemd to be the slowest of them all and Mitsuba fastest. So did anything changed in past time?
Right now I did 3 test Cycles, Mitsuba 0.4.3, Luxrenderer. All engines were setup with same material, engine settings and lightning (HDR image). Render setup was Path Tracing with 128 samples. (update) For Luxrender i used Metropolis sampler, and paused it at 13min so I’m not sure how many samples there were(/update). Below are result with render times and renderer settings.


Difference between Cycles and Mitsuba in not that big. It is step forward compared to year 2011, where cycles gave more noisy renders (much worse than Luxrender). But then how much longer will it take to clean up Cycles render? Here is render made with 256 samples (image label is wrong, sry) and twice the render time.

Cycles render is still not as clean as Mitsuba. So thing is even thought Cycles speed improved quite a bit, it requires a lot more time, than Mitsuba to denoise image (probably 512 samples would suffice – but it would require about 1 hour). On the other hand interactive preview of scene, in Cycles, makes creation of shaders very fast!
About Luxrender, I’m not sure If my setup was correct but it seems slowest – (update) even with Metropolis sampler and QBVH. SQBVH build time was something like 9 sec, QBVH -2sec – but those numbers are from my mind. Anyway this is small % of overall time.
And one more screen with example of material setup for wheels:

In Mitsuba to setup metal material I just put chemical symbol – MgO (Magnesium Oxide), and it’s roughness – 0.08
Luxrender support metal nk data too, however loading MgO.nk file caused error, so I set it up with bronze metal. I’m not sure why pylux didn’t worked for material preview. Maybe because of using latest unstable Blender build.
Cycles has material setup similar to Lux – bronze glossy material, with 0.08 roughness.
Update:
And bunch of cycles tests -progressive vs non-progressive sampler, HDR MIS ON and OFF.

PS
Car model – Lexus CS 2054 form Minority Report – is not mine. You can download it form here.
My setup is – AMD 3 core, 2,6GHz, 8GB of ram DDR 2. Is is very old, so on newest hardware, you could probably expect half the time to render those images.