pgsql-bugs(at)postgresql(dot)org writes:
> The backend call lseek much more often than it has to.
Denis Perchine fixed this a couple of months ago. You might care to
repeat your experiments with current sources (see our CVS server, or
the nightly snapshot tarball on our FTP server). If there's still
a problem we'd like to know before it's too late to tweak 7.1 ...
regards, tom lane