In this example, we specifically ask Git to consider all of the commits in the history by supplying the --all switch. Git runs through the DAG and checks whether the "Performance" string is included in the commit message. For an easy overview of the results, the --oneline switch is also used to limit the output to just the subject of the commit message. Hopefully then, the commit(s) we needed to find can be identified from this, much shorter, list of commits.
Note that the search is case sensitive—had we searched for "performance" (all in lower case), the list of commits would have been very different:
$ git log --grep "performance" --oneline --all d7deda98d Skip ignored directories in FileTreeIterator5a87d5040 Teach UploadPack ...
