I tried my best to be as transparent and fair as possible, running everyone with out-of-the-box settings on a third party's queries (DuckDB), a third party's data generator (tpcgen-rs, from the DataFusion guys), on a stock setup available to everyone (AWS machines).
The one exception is that we also ran Polars locked to 32 threads on the large machine (in addition to the out-of-the-box setup), which was to highlight we can do a lot better on small data. We still suffer from a relatively high constant overhead on very high CPU count machines if the data isn't large enough, but I'm working on fixing that. It's possible that DuckDB / DataFusion have similar scaling issues with high thread counts and would do better with 32 threads as well, I didn't test that.