I am making my way (sometimes painfully) through an online "intro to Blender" course and have got to the Lighting section, in which the end-of-class exercise is to light a scene using Cycles. I am running Blender (Steam version) under El Cap, GTX970, latest WebDriver and CUDA driver from NVIDIA. Based on Heaven and other benchmarks (3d sims), this a fairly capable graphics platform.
However, I'm finding Cycles incredibly slow to render just one frame of a (not too complex) scene. So slow, in fact, that I don't think I can afford the time to do the exercise! Blender Render will render the scene in about 25 seconds, whereas Cycles was getting only a small fraction rendered in 25 seconds, less than .10 of the total image area. I did enable CUDA and I did select GPU for the Cycles render hardware, and nothing seemed to help.
I have read a lot of conflicting info online, much of it obsolete (old posts), and am confused. Was wondering if anyone here has a pointer to a really definitive reference on speeding up Cycles on NVIDIA hardware. I did find and install "blenchmark" but when I tried to run it w/o GPU, to compare my CPU vs GPU render times, it crashed :-(
In the meantime I "de-noded" the meshes in the scene and tried to light it with BI, but the results were not nearly as impressive as other people achieved with Cycles. I would like to try again with Cycles if I can find out how to speed it up a bit! If I reduce "samples" from 2000 to about 100 I can get Cycles to render the scene in 30 sec or so, only a little slower than BI, but the quality is awful (grainy); I won't get an acceptable image to submit for grading that way!