+=head1 PERFORMANCE NOTES
+
+L<Inline::C> is required, lei runs as a background daemon to reduce
+startup costs and can provide real-time L<kqueue(2)>/L<inotify(7)>
+Maildir monitoring. L<IO::KQueue> (p5-IO-KQueue on FreeBSD) and
+L<Linux::Inotify2> (liblinux-inotify2-perl and perl-Linux-Inotify2 in
+.deb and .rpm-based distros, respectively) are recommended.
+
+L<Socket::MsgHdr> is optional (libsocket-msghdr-perl in Debian),
+and further improves startup performance. Its effect is most felt
+when using shell completion.
+
+=head1 BASH COMPLETION
+
+Preliminary Bash completion for lei is provided in
+C<contrib/completion/>. Contributions adding support for other
+shells, as well as improvements to the existing Bash completion, are
+welcome.
+
+=head1 UPGRADING
+
+Since lei runs as a daemon, L<lei-daemon-kill(1)> is required to kill
+the daemon so it can load new code. It will be restarted with the
+next invocation of any lei command.
+
+=head1 CAVEATS
+
+IMAP and NNTP client performance is poor on high-latency connections.
+It will hopefully be fixed in 2022.
+