> I don't understand what this table means (why 4 columns?). Can you explain what you did?

Yury suggested running perf.py twice with the binaries swapped
So "faster" and "slower" underneath "Baseline Reference" are runs where the unmodified python binary was the first argument to perf, and the "Modified Reference" is where the patched binary is the first argument.

ie. "perf.py -r -b all python patched_python" vs "perf.py -r -b all patched_python python"

bench_results.txt has the actual output in it, and the "slower in the right column" comment was referring to the contents of that file, not the table. Sorry for the confusion.