A regression is only actionable once one owner is named. The move is to bisect: change one variable at a time and keep the rest fixed, so the difference you see belongs to that variable and nothing else.
About 1 min of reading
Before this new lesson, one small question about the lesson you just finished. Recall it, do not look it up.
Bisect to one owner
Fix the settings
Before you run it, say out loud what it will print. Then open the answer.
Measure the baseline
Before you run it, say out loud what it will print. Then open the answer.
Remove half and re-measure
Before you run it, say out loud what it will print. Then open the answer.
Write the report line
Before you run it, say out loud what it will print. Then open the answer.
Two moving variables produce a difference that belongs to neither. The cost of fixing the rest is a few more runs, and the gain is a claim you can act on.
If no single asset explains the gap, the owner is a feature. Bisect features the same way, by disabling one and re-measuring.
Same connection, same sample count, same viewport, same cache state. If two variables move together, the measurement tells you nothing about either.
Remove half the assets, measure. Still slow: the owner is in the half you kept. Fast: it is in the half you removed. Three rounds names one file out of eight.
The report line names the file, the number, and the threshold. A report that names only the number cannot be acted on by anyone else.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.