In Independence Day 2: Resurgence, you're the Super Intelligent Hive-Mind Queen. Over a billion entities can be attached to your brain, but far less seem to be in this sequel than the first, so you should have even more available mental power.
Your Mission: Capture and destroy your arch-nemesis and only real threat: The AI Sphere.
Your mothership has been cold-nuked from within by a valiant ex-President. All of your support staff is assumed injured or dead.
Your Primary Planetary Objective is almost complete (mere minutes to go).
This will result in the imminent Destruction of the Planet. Better be outside of Earth's gravity well in the next 30 minutes!!
You are continuously being strafed by several fighter craft.
You are in an inhospitable climate, running across difficult terrain, and you have just crash-landed at several G forces, so maybe you are not at peak physical health?
You know exactly where the AI Sphere is. [With Jeff Goldblum], or so you think.
Why do you expend so much time and energy inefficiently chasing a school bus?
From the movie it didn't appear that she was particularly interested in chasing the school bus. They just happened to be going in the same direction, back to the main base. If she really wanted she could have stepped directly on the bus or blasted it with her huge gun, but did not.
On the other hand, all the humans that just successfully executed their plan to trap your ship are fleeing on the big yellow vehicle, so if it gets destroyed in the process that would be fine.