Marat Radchenko venit, vidit, dixit 23.08.2011 12:52: >> Is that a very large tree or a very slow file system? > Tree is large (500k files), file system is irrelevant since all time is spend on CPU. > >> Do we enumerate all >> differing files and only then limit diff output by path?? > > Dunno, that's why I am asking why it is so slow. Well, we have to read the full tree before diffing. But I can't reproduce the extreme difference which you observed (0.003s vs. 30s), only a factor of ten or so for a repo with 100k files: git init seq 0 100000|while read n ; do echo a > a$n;done git add . git commit -m m echo b > a0 On a ramdisk, I get: time git diff > /dev/null real 0m0.160s user 0m0.064s sys 0m0.190s time git diff -- a0 > /dev/null real 0m0.070s user 0m0.051s sys 0m0.021s time git diff HEAD > /dev/null real 0m0.266s user 0m0.145s sys 0m0.212s time git diff HEAD -- a0 > /dev/null real 0m0.171s user 0m0.136s sys 0m0.033s time git show HEAD:a0 > /dev/null real 0m0.018s user 0m0.009s sys 0m0.007s time git show HEAD:a0 | diff -u - a0 > /dev/null real 0m0.019s user 0m0.010s sys 0m0.008s Stumped. In your case, do you have a lot of differing files besides the one you are limitting to? Anyway, that does not seem to make a huge difference in my timings. (Just tried.) Still Stumped. Michael -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html