Please understand, I am very much getting my feet wet, so this might sound silly.
I was messing with the connectfx color warper.
Rendering seemed really slow for the little workflow I was testing. I wasn't doing anything drastic, just a little color balancing out of log, and a render to ProRes HQ.
CPU was hovering around 150%. I am on a fibre SAN, so perhaps it's choking on the frames and I didn't have time to move to local storage, but I'll try as soon as a find more time. Playback of 444 ProRes seemed just fine.
The weird thing was, when I let Smoke sit, the CPUs would sometimes spin up to 200+%.