Adobe Media Encoder (Why is it not using all the available power)
So after quite some time it turns out ame is pretty useless on using as much comp resources as you have. I did how ever find a really solid solution. Rendergarden is a third party tool that splits the output render into chunks and renders them all in parallel. I went from using no more than 3% cpu to render garden using as much as I asked ie 96%.
This axes render times by a factor I genuinely cannot believe. In real terms it cut a 3h 52min render into a 24min job. (16 CORES SMASHES THROUGH RENDERS)
It does cost money but if you are experiencing this issue this 100% removes the media encoder render bottleneck.