The Starsling Kingdom's navy's ships slowed down because the mana crystals powering the enchantments that drive and protect the ships were running out of mana. Unless the soldiers stop and swap the mana crystals, they'll end up having to withstand the Void's pressure without the ship's help.
Due to the automatic mana-absorbing enchantments, they rarely have to swap out the mana crystals. Usually, that is only a good thing, but when they put in new crystals, the soldiers have to put the ship on standby so that it doesn't burn through all the mana before the new crystals are in place.
While several of the ships began dropping out of the race, the two ships in the lead, Dristel's and his captain's, remained unbothered as they kept chasing Toz.
Toz looked on in satisfaction as the Starsling Kingdom's navy's arrival had made their contingency plan a booming success.