Xanthir, that's an interesting point you raise. On an infinitely fast computer, emulating a mind at infinite speed, that mind would actually experience infinite subjective time between instructions from an external operator. It would, perhaps, be a good idea if the infinitely fast computer had two modes: "interaction" and "operation". Interaction mode would have the processes run at whichever speed is required. Operation mode executes a bounded region of code at infinite speed. If the boundary of that section is reached (which it will in zero objective
time or finite subjective
time), the computer is reset to interaction mode. The picture-sorting mind would experience normal time when it is in interaction mode, and would experience a very long but not infinite span of time when it starts to sort those pictures.
Of course, the advantage of a digital consciousness is that it would be possible, or could be made possible, to "retcon" that mind. Suppose you have a googolplex images you want to sort through, on a stack $images[(googolplex)]. You give the mind the first image. It decides if the image is worth keeping - if so, it is pushed to the output pile, if not, it is discarded. The image is popped off the stack; length($images) is now (googolplex-1). You jump back of the start of the subroutine and repeat until length($images) is zero. When the mind is processing, it only ever experiences having sorted 0 or 1 images (ergo, it does not tire, since looking at a single image and deciding whether it is worth keeping is trivial). When it is done
processing, it has experienced processing zero
images. Letting the mind operate like this has two distinct advantages: (A) it is kept in sync with the real universe, as in the end, it has no recollection of ever spending any subjective time, while according to the outside universe, it has also experienced zero objective time - and (B) at no point does it ever experience having looked at more than one image. Voilà, problem solved.