Drake slowing down as I build a larger plan

As I'm building a drake plan out to include more and more steps, I'm finding that make(plan) and vis_drake_graph() are taking longer to start executing.

For instance, to visualize the dependency graph in this example notebook takes about 1.25 seconds. My drake plan on the other hand has 35 targets and it takes 17 seconds to run the same command. There is a similar delay for targets for make(plan) to start creating targets.

I'm guessing the triggers are taking long to compute, but I'm not sure what to try here to confirm that without losing some large, cached targets. What would be your game plan on diagnosing this delay safely?