I tried making something simple. And lo and behold, 100% cpu usage was reached! There must have been something dodgy with that previous file.
This was the bugged, final render that took 3 days to output.
hesus_9_hard.jpg
This is a just for fun SU output render
jesus,house_resive.jpg
This proves that the previous file was bugged and that everything is working back to usual.
100%.png