Comment by wasyl

> Shown as a hierarchical bar chart, this would suggest 'b' is problematic.

But it's not necessarily `b` that's problematic:

- it may be `a` because it does a lot of stuff on its own, and depending on what `a` is, it might not be expected

- it could be `d` if it's supposed to be super fast (e.g. a logging method)

- it could be `c` because it takes a long time

- it could be `b` if `c` is external code or if calling `c` from `b` is not appropriate for what `b` does

- it might be nothing because there's nothing to optimize anymore, things just take this long

in fact, `b` is the last method I'd look at here