Got to say, I'm loving RC5! Been working away on a packaging render all day, not a single crash.
With the IRR on in c4d the previews are pretty snappy, maybe 1 or 2 secs before an image appears, and it cleans up quite quickly. If this is a taste of things to come, then it could be THE renderer for c4d, at least on the cpu side. I'm on a 12 core 3.46GHz Mac Pro and I'm very happy with the performance.
Very excited to see what's coming in later releases.
Well done to the devs!