Nice tool. Looks like it uses what we now call a "flame chart" (not a flame graph). I don't know if it ever had an original name, but I've seen these in tools from at least the 1990's.

If I understand correctly, your plot is different because you aggregate all of the sampled data; which is in itself quite useful, btw.

While I was going through my B.Sc., I worked a lot with performance optimization, this was around 2008. I used many tools which were slight variations on the idea of visualizing stack traces. I don't recall if that specifically was a thing or not. I believed it was something that has been doing for decades perhaps, because I was touching gdb, perf, etc... I am now reading about it and turns out that the visualization side of it is relatively recent (not 80s but 00s).

Anyway, I apologize for my initial comment being that harsh, I still think you're cool! :D