The minimum amount of energy needed to compute decreased asymptotically to 0 as the temperature of space goes to 0. This is the reason a common sci-fi trope where advanced civilizations hibernate for extremely long times so that they can do more computation with available energy.
In the book Calculating God, a character notes that this is a common civilization-wide choice. Living in virtual reality, rather than trying to expand into the vast expanses of space, is a common trope as much as it's a logical choice. It neatly explains the Fermi Paradox. In some fiction, like The Matrix, the choice might be forced due to cultural shifts, but the outcome is the same. A relatively sterile low-energy state civilization doing pure processing.
True. But it's not a binary choice. All it takes is to make one sub-optmial choice for the universe to be filled up with von-neuman probes in all star systems
