What a obnoxious write-up for a pretty straightforward optimization. I don't really see how this is worthy of any discussion, unless we want to discuss how some developers think they're a lot more clever than they really are.
"Developer profiles code; replaces slow library call A with faster library call B; ensures B does not change any important behaviour; writes self-congratulatory pull request."
"Developer profiles code; replaces slow library call A with faster library call B; ensures B does not change any important behaviour; writes self-congratulatory pull request."