I find the discussions of Decision Theories a little ethereal sometimes. There is a base assumption that Eliezer has made that the manner of making the decision doesn't matter. So questions of energy efficiency or computational resources used when making a decision don't come into the discussion. I personally cannot justify that assumption looking at the evolutionary history of brains, i.e. stuff that has worked in the real world. It matters how big the brain is, the smaller the better if you can get away with it. The simpler the better, if you can get away with it, as well.

Quote from a Newcomb's Problem article

We can choose whatever reasoning algorithm we like, and will be rewarded or punished only according to that algorithm's choices, with no other dependency - Omega just cares where we go, not how we got there.

It is precisely the notion that Nature does not care about our algorithm, which frees us up to pursue the winning Way - without attachment to any particular ritual of cognition, apart from our belief that it wins. Every rule is up for grabs, except the rule of winning.