jorisvandenbossche commented on issue #38260:
URL: https://github.com/apache/arrow/issues/38260#issuecomment-1762889496

   I was going to comment yesterday that this is quite likely an issue on the 
pandas side, which is in the meantime confirmed by the comments above. And 
coincidentally, I was now looking at a perf regression report in pandas 
(https://github.com/pandas-dev/pandas/issues/55245) that shows the same culprit 
as in the py-spy image from @amoeba above: `Manager.iget`, which is what is 
used under the hood to access a column.
   
   So it's indeed repeated column lookup in wide dataframes that has become 
significantly slower. It's a regression in 2.1.0 -> 2.1.1, and caused by 
https://github.com/pandas-dev/pandas/pull/55008#issuecomment-1759810383


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