It's *very* difficult to say, given that we've got much better branch prediction...

It's very difficult to say, given that we've got much better branch prediction, caching, pipelining of instructions, SSE (4 float ops at once), etc.

On top of that, different rendering algorithms, optimisations, biased-vs-unbiased.

http://imgur.com/MIFWC

For example, took 12 seconds to render on a quad core i7, but that's 512 unbiased samples per pixel, and 5 bounce global illumination, so that's around 2,013,265,920 rays sent in 12 seconds, which isn't bad.