I don't want to hit it with the poorly optimized label, @SeashoreLivia, but there are a number of moving parts which will happily eat whatever your GPU and CPU will give it.
One of the things mentioned in the new update is random sniff points generated in the exhibits. That is just one example of all the stuff we cannot see that is constantly active. NPC pathing can be horrific. All the guests have thoughts, needs, and behaviours. Every bit of scenery is more rendering. All the animals gave pathing, needs, behaviors, etc. I can understand why laptops in particular will chug (having a gaming laptop myself).