Hi davidcl,
under new macOS 10.13.4 on an iMac 5K I have the same issues with VLC 3.0.1.
Maybe you can try transitionally a nightly Version of VLC 3.0.2 and change back on a stable version when 3.0.2 is officially out.
You can download a nightly version at https://nightlies.videolan.org