Option A here. Parallel branches let both Update Row actions run simultaneously, which is the best way to save time if they aren't linked. Some might pick B thinking about possible data locks, but with no dependencies mentioned A fits. Let me know if you disagree.
Minimizing processing time definitely fits with A here. Parallel branches let those two Update Row actions run side by side, instead of waiting for one to finish before starting the other. The only catch is if there was something about Dataverse throttling, but since that's not mentioned, pretty sure A is right. Anyone see a scenario where B would make sense?