absurdly slow git-diff

I have a 240k-line file, and I change one character on every sixth line. The resulting diff gives git serious indigestion:

$ git --version git version 1.6.0.3.640.g6331a $ mkdir a; cd a; git init Initialized empty Git repository in /home/ams/a/.git/ $ cp ../1 .; git add 1; git commit -q -m 1 $ cp ../2 1; git add 1; git commit -q -m 2 $ time git show HEAD > x git show HEAD > x 309.88s user 0.46s system 97% cpu 5:17.06 total

(I use commit -q above not only for brevity; for the second commit, calculating the diffstat takes the same five minutes that git show, git log -p, git log --stat etc. all take.)

Note that diff(1) can handle the patch fine:

$ time diff -u ../1 ../2 >/dev/null diff -u ../1 ../2 > /dev/null 0.30s user 0.06s system 69% cpu 0.519 total

If anyone's interested, the files are http://toroid.org/misc/1 and http://toroid.org/misc/2

Does anyone understand why this slowdown might happen or have suggestions about where I should look for it?

Thanks.

-- ams