When opening a .diff file, GNU Emacs runs "diff -ad" on 2 files it has built (I suppose that the reason is to get a word diff), and this can be very slow, even though the original .diff file is rather simple. I've attached a slow-diff.tar.xz archive with: * diff1L52tn0 and diff2U4TVho (files built be GNU Emacs). * file.diff the original .diff file. When running "/usr/bin/emacs -Q file.diff.xz", I could see what takes the whole time with ps or top. Here I could see diff -ad /tmp/diff1L52tn0 /tmp/diff2U4TVho As this is slow, I could obtain these files. On my recent machine, "diff -ad diff1L52tn0 diff2U4TVho" takes 27 seconds. -- Vincent Lefèvre - Web: 100% accessible validated (X)HTML - Blog: Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)