It was a big relief that the Ancient Tree of the Netherworld was able to leave safely. It was originally a plant. After spending years listening to the Ksitigarbha Bodhisattva preach about Dao and the long-term absorption of filthy Qi of the Netherworld, it evolved to its current spiritual form. Despite that, the speed of its light traveling skill was just average and would never be able to travel from the North Sea to the southern Mount Changwu within a day.
In order to escape from the group of people earlier on, the Ancient Tree did not hesitate to use its divine Qi to speed up its light travel. When it felt that it had traveled far enough and was exhausted, it slowed down.