On 2010-02-09, Oliver Charles wrote: > I just upgraded to xapian-core HEAD and notmuch master tip today, in > desparation to get away from GMail. Sadly it's still taking at least > 0.7s to tag a single thread (with one message). I'm really eager to > solve this, could anyone give me any pointers on how I could go about > profiling it or finding the cause of this problem? The first thing to try is disabling use of F_FULLFSYNC. You'll need to run this command in the xapian-core source tree to comment out the F_FULLFSYNC code: perl -pi -e 's/^#ifdef F_FULLFSYNC/#if 0/' backends/*/*_io.h Then run "make" and "make install". This makes you a bit more vulnerable to power failures, but no worse than a typical Unix system. There's some background here: http://lists.apple.com/archives/Darwin-dev/2005/Feb/msg00072.html Assuming that helps, then (a) you have a workaround, and (b) we'll know for sure it is F_FULLFSYNC to blame. I've created a ticket for a change to Xapian which should help here, but not had a chance to work on it yet: http://trac.xapian.org/ticket/426 Cheers, Olly