Whats the hardware? How much electric energy goes into rendering a frame or a whole movie? How do they provision it (as they keep #cores fixed)? They only talk about cores, do they even use GPUs? What's running on the machines? What did they optimize lately?
So many questions! Maybe someone from Pixar's systems department is reading this :)?
ex VFX sysadmin here. I'm not sure if they use their own scheduler or not. IF they do, they use tractor(might be tractor 2 now), which looks after putting the processes in the right places. Think K8s, but actually easy to use, well documented and reliable. (just not distributed, but then it scales way higher and is nowhere near as chatty)
They would have a whole bunch of machines, some old some new, some with extra memory, for particle sims, some with extra cores for just plain rendering. Each machine will be separated into slots, which are made up of a fixed number of cores. Normally memory is guarded but CPU is not (ie, you only get 8 gigs of ram, but as much CPU as you can consume. Context switching the CPU is fast, memory not so much.) I'm not sure on how pixar does it, but at a large facility like ilm/framestore/dneg the farm will be split into shows, with guaranteed minimum allocation of cores. this is controlled by the scheduler. crucially it'll be over subscribed, so jobs are ordered by priority.
As for actual hardware provisioning, thats quite cool. In my experience there will be a bringup script that talks to the iLo/iDrac/other management system. When a machine is plugged in, it'll be seen by the bringup script, download the xml/config/other goop that tells the bios how to configure and boot from the network, connect to the imaging system and install whatever version of linux they have.
As for power per frame, each frame will be made up of different plates, so if you have a water sim, that'll be rendered separately, along with other assets. These can then be combined afterwards in nuke to tweak and make pretty without having to render everything again.
That being said, a crowd shot with lots of characters with hair, or a water/smoke/ice effect can take 25+ hours per frame to render. So think a 100core/thread machine redlining for 25 hours, plus a few hundreds TB of spinny disk. (then it'll be tweak 20ish times)
optimisations wise, I suspect it's mostly getting software to play nice on the same machine, or beating TDs to make better use of assets, or adjusting the storage to make sure its not being pillaged too much.