Blender Institute prepared six Blender files for testing Cycles rendering with CPU/GPU, using various settings and design styles but based on actual production setups. On the links below you can inspect the spreadsheet with results, and load the .blend file collection.
The goal is to have an overview of systems that are used or tested by developers of Cycles. We aim at updating it regularly, also when new hardware comes in – and especially when render features improve in Cycles.
Most strikingly so-far is that the performance of CPUs is in a similar range as GPUs, especially when compared to costs of hardware. When shots get more complex, CPUs win the performance battle. That confirms our own experience that fast GPU is great for previewing and lighting work, and fast CPU is great for the production rendering. But… who knows what the future brings.
Feel free to post own stats and observations on this blogpost! Maybe other .blend files should be added?