This histogram strategy was introduced in git 1.7.7 (Sept 2011), with the following description (as mentioned by the OP) "git diff" learned a "--histogram" option to use a different diff generation machinery stolen from jgit, which might give better performance. JGit includes src/org/eclipse/jgit/diff/HistogramDiff.java and tst/org/eclipse/jgit/diff/HistogramDiffTest.java The description there is