I loaded up a scene in p8 that had taken p7 two and bit episodes of Babylon5 to render, (sorry I can't be more specific). P8 rendered it in 35mins. I have a quad core, but beyond that I couldn't say.

I mostly like the new UI. It'll take a bit of getting used to but that's ok. Not at all sure about the teeny tiny thumbnails in the library though. Is there a setting you can change to get them back to a better size? I know you can click each individual thumbnail to get a bigger one, but seriously, that's going to be a huge pita.