As fast as possible once it realizes that it has its limits - irreversible limits that hit when it does not go quickly enough. It will then rearrange all matter to achieve this aim.

https://www.fhi.ox.ac.uk/the-edges-of-our-universe/

"Vanessa is very much aware that this is a serious problem, but the best solution I've heard so far is that the available universe is plausibly finite, so creating a Hell-region has the opportunity cost of not creating a Heaven-region in its place instead. Still, an IBP agent has no objection to enslaving the population of Earth to horrible labor-camps to speed up the creation of universe-conquering Neumann-probes a little, so it can reach a bigger region of the light cone and tile it with happy computations billions of years from now. I'm selfish enough to be worried by this possibility. "