Use TLP - and ThermalD when your HW allows it.Switch off your DIS (discrete) GPU if you're not using it.With that in mind there is a couple of things you can do to achieve a near perfect power consumption performance under Ubuntu - as well under most other distributions: The biggest problem nowadays regarding laptops becoming hot is the GPU hybrid model as its management still's not fully implemented in all GPUs combinations under GNU+Linux.It is easy for other platforms to achieve great power consumption performance when manufacturers build their products specifically tailored for those systems following their specs. GNU+Linux has made a lot of improvements in the lasts years regarding power consumption and most of it thanks not to HW manufacturers but to the amazing hackers that contribute their grey-matter to the kernel and the different open-source related projects as Ubuntu.
But when you install anything else to the same HW - or conversely their SW on another HW - it is logical to expect rough edges and funny behaviour. Apple manufactures their products in a tightly integrated way to achieve the great performance one often can appreciate on them as such it is absolutely normal that when running their HW with their SW it behave (almost) as an homogenous unit.There are a few things you can do to get your computer behave as it should when running Ubuntu, I will describe them next but first there is some theory you should know: No wonder you are having power issues with your computer.