Something I've learned is that it will use a lot of CPU even if the video is paused.
this has been my experience with it on windows too, so it must be a core VLC thing. if it bothers you, I recommend you to try out MPV. been using it for more than a year, would never go back. If you need more than the on screen controller and key combos, there are quite a few proper GUI players being built on MPV.
D-Bus is a system service that is used by processes to communicate with others. It's commonly used, but as users we rarely see anything of it. It's usage for programmers and sysadmins is/can be quite complicated. It looks they want to add a new simpler one. Haven't heard of varlink before, though