WORK IN PROGRESS
Your functions take time to execute (as seen on flame-graphs) but they also spawn asynchronous requests and pass a callback to regain control of the program flow.
Here's a tool to visually understand how time is spent in your app.
dprof - not much to add here, just follow the readme.
What's the difference between dprof and flame-graphs?
In flame-graphs, time is the value represented on the graph, dprof also visualizes the relationships between functions and their callers.