-L<Inline::C> is recommended for performance. To enable it, create
-C<~/.cache/public-inbox/inline-c/>.
+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.