Hi Mitch, it had been discussed excessively in the past and I’ve been told by McNeel that the 10.9.5 was not well with rendering. (Read about it here: Rendering time comparison (example file included))
I’ve upgraded to Yosemite at the time and this improved rendering massively. However, I haven’t been rendering for some time and now I try to render a simple scene and it appears to be bugged again.