Enormous timeout in Clock plug-in
xfce4-panel was taking 18 seconds to start on my fast, 16-core i7 box. When I enabled PANEL_DEBUG, it turned out that the Clock plugin was waiting for all of that time "xfce4-panel(clock): trying to instantiate logind sleep monitor". After the long wait, it then reported "libclock-Message: 15:56:17.194: could not get proxy for org.freedesktop.login1" and "(xfce4-panel:18336): libclock-WARNING **: 15:56:17.195: could not instantiate a sleep monitor" before allowing start-up to continue.
My Devuan Linux box does not run logind. (An Xorg user session is started with startx.)
I removed the Clock plug-in from the panel, closed the panel and restarted. Starting of the panel was instantaneous.