Flame graph
Also called Flame chart
A picture of a profile. Each bar is a function, sitting on top of the one that called it, and the wider the bar, the more time it took. You look for the wide bars at the top: they are doing the work themselves, with nothing above them to blame.
A flame graph lets you check an agent's story at a glance. If it says the slowness is in the formatter and the widest bar is somewhere else, you can see that for yourself without reading a line of code, and without taking its word for it.
Say it to your agent
“Run py-spy record -o profile.svg -- python report.py and tell me the three widest frames with nothing above them, with their percentages. Propose a change only for those, and rerun it afterwards to show that frame got narrower.”