The discontinuity would increase as subjective time per instant decreased and as subjective change per instant increased. If you have a lot of changes but also a lot of subjective time, it's fine. So running at faster speeds is fine, as long the number of subjective steps are the same.

Yes, the idea, simply put is that eventually the universe will be filled with utilitronium, and I'm asking whether anything that goes on before that can impact the value of the utilitronium, i.e. the maximal amount of value.

Given that most plausible cross-temporal dependency we know of are on cases of continuity, then the transition from humans to a superintelligence is the best candidate here. Which means they would be before the creation of a superintelligence.