Inteligence is not one dimensional as is evolution => https://backchannel.com/the-myth-of-a-superhuman-ai-59282b68...
Silicon based intelligent machines might not energy efficient => https://aeon.co/essays/intelligent-machines-might-want-to-be...
A choice quote:
In contradistinction to this orthodoxy, I find the following five heresies to have more evidence to support them.
Intelligence is not a single dimension, so “smarter than humans” is a meaningless concept.
Humans do not have general purpose minds, and neither will AIs.
This is awfully similar to "On the Impossibility of Supersized Machines" (https://arxiv.org/pdf/1703.10987.pdf).
EDIT: Re: energy efficiency: the problem is that humans are too energy efficient. Your brain can keep functioning after 3 days of running across the Savanna without food, which is (a) awesome, and (b) not really helpful nowadays. The cost of this is that you can only usefully use a little energy each day, say 4 or 5 burgers at most. AGI prototypes will usefully slurp in power measured in number of reactors.
On the second point, who cares? If the first AGI draws gigawatts, it will still be an AGI.