I don't think your numbers are correct. My Core i7-4770K (4 cores) runs povray --benchmark faster than your 12 core Xeon:

    Render Time:
      Photon Time:      0 hours  0 minutes  1 seconds (1.256 seconds)
                  using 11 thread(s) with 1.456 CPU-seconds total
      Radiosity Time:   No radiosity
      Trace Time:       0 hours  2 minutes 18 seconds (138.426 seconds)
                  using 8 thread(s) with 1099.214 CPU-seconds total

That's POV-Ray 3.7 with no architectural optimizations. I just apt-get installed it.

I would be very surprised if the Chromebook's 1.8GHz Cortex-A17 was only 3x slower. Googling around, I see people mentioning numbers like 10,000 CPU-seconds.