I found this patch that might fix it: https://quickgit.kde.org/?p=plasma-pa.git&a=commit&h=aa5efa1344ab34ffc580d73669b1eb2bd77d416c The referenced bug is https://bugs.kde.org/show_bug.cgi?id=366320 ("Heavy CPU usage when pulseaudio fails to start") So if there are many references to pulse in the log output, this will likely work around it (pulseaudio not starting is the real issue that should be fixed, no idea why it just happens when the screen is locked)