I think the heuristic is really easy: "Is it slower than before?"
If it's slower, then you require a manual override to accept the merge.
That will make performance regressions a whole lot less likely. Sure, in some cases they may be necessary, but in many cases they were unintentional; they can be fixed, and then merged.
If it's slower, then you require a manual override to accept the merge.
That will make performance regressions a whole lot less likely. Sure, in some cases they may be necessary, but in many cases they were unintentional; they can be fixed, and then merged.