I'm not including parsing time, both pandas and polars versions started from an in-memory data structure parsed from two XML files (low GB range). This is on my workstation with a single Xeon 4210 (10 cores, 20 threads @ 2.20-3.20Ghz).

Perhaps I can focus on a subset of this processing and write this up since it seems like there's at least some interest in real examples. As pointed out in a reply to a sibling comment, I don't guarantee that my starting code is the best that pandas can do -- to be honest, the runtime of the original code did not line up with my intuition of how long these operations should take. Maybe someone will school me but either way switching to polars was a relatively easy win that came with other benefits and feels right to me in a way that pandas never did.