I've recently noticed that the pulseaudio plugin is causing constant CPU load that can be measured (using htop) to 10%-15% on my system. This is very bad since it means not only reducing available CPU time for other programs but also draining the battery unnecessarily.
I can reproduce this with 0.2.4. I've tried disabling notification on volume changes and it didn't reduce the CPU use.
Please let me know if you can reproduce this. If not, I'll try to find some time to debug it. However, I can tell already that PANEL_DEBUG=all does not list anything helpful.
I can't reproduce this issue here (xubuntu 15.10 and older). Please let me know if you spot anything.
Does the problem occur when you use other pulseaudio mixers like pavucontrol?
Well, 'kinda'. pavucontrol takes around 5% CPU (compared to 15% for pulseaudio plugin today).
Ok, so some stracing and I have some results. Both in case of pavucontrol and xfce4-pulseaudio-plugin, this seems to be caused by intensive polling from /tmp/.X11-unix/X0 socket. Basically, it is constantly reading some small messages from that socket.
That considered, I guess it's not xfce4-pulseaudio-plugin to blame. If you have any suggestions where to look next, I'd appreciate.
Ok, after some debugging it turned out to be poor GTK+3 Xfce theme spamming X11 with render requests. Sorry for the noise.