Don’t use FileMerge with 25mb files

How long does it take to use OS X’s FileMerge on a pair of 25mb files? Somewhere between 20m and 2 hours. I left my computer after 20m since it wasn’t done, but it was when I came back. At this point, I’m convinced I don’t need to worry about using PyPy with Skeinforge, so I can start saving time. Now if I could only quadruple the speed of my ToM…