I should respond to Kory's ME == PE idea. In PE we find such things as "thermodynamic entropy" and "temporality". If we are to take Kory's idea (that Mathspace doesn't require resources) seriously, ME does not. This seems a direct contradiction! Perhaps Kory has a paper on-line that lays out his thesis of "Instantiationism".
No, I wish had the energy to write such an online paper. :) Anyway, please note that my own position is not "Instantiationism". This was the word I used to describe the position that I *don't* accept - i.e., the idea that computations need to somehow be physically instantiated in order for them (or more importantly, the SASs within them) to be "real" or "conscious". If I had to come up with a name for my position, I might call it "Mathematical Physicalism".
I have to confess that I'm not sure I'm following your argument. Are you referring to the tension between the static view of Mathspace, in which there is no concept of "resources" and computational structures exist "all at once", and the dynamic, 1st-person view that we have as creatures, where time exists and resources are limited? I'm willing to admit that there's tension there, but it seems to me that the tension exists for the Instantiationist as well as the Mathematical Physicalist.
All I can do is trundle out the same old thought experiments that we're all familiar with. Imagine a 2D CA in which the state of each cell is determined by the state of its neighbors one tick in the "future" as well as one tick in the "past". Such CA cannot be computed "one tick of the clock at a time" like a regular CA. Instead you'd have to consider the whole structure as a 3D block of bits (one of the dimensions representing time) and somehow "accrete" the patterns within it. Or you could do a brute-force search through every possible block of bits, discarding all those that don't follow the rules. Some of the universes that you're left with may exhibit "thermodynamic entropy" and "temporality" - we can imagine a particular block universe that contains patterns which represent observers moving around, interacting with their environment, etc. - and yet from our perspective the whole structure is entirely static.
There certainly seems to be a kind of mystery when we think about "temporality" within this static structure. We can "follow along with our finger" and "watch" some creature - some pattern of bits in the block universe - struggling valiantly against some obstacle in its environment. Yet clearly our act of following along with our finger is not suddenly making that creature conscious. The computations have already been performed - the entire block universe has already been physically instantiated. All we're doing now is observing it, like looking at the frames of a film. So at what point in time was that creature actually conscious? Did it happen "all at once" when our computation "found" that block universe? These are deep and murky questions, and I don't see how the idea of "physical instantiation" makes them go away. Indeed, it's precisely these "block universe" scenarios that suggest that it *does* make sense to view our universe as existing "all at once" out there in Mathspace, even though I'm in here perceiving it in this temporal fashion.