I am a huge GNOME fan (the interface, the ideas behind it, the look). But I made my peace with the fact that I need stability and performance so Kubuntu 18.04LTS it is (edit: and Gnome hasn't achieved UI coherence yet despite being 10 years in the making,so...).

Performance issues shouldn't appear between LTS-1 and LTS. Ideally LTS should be the polished and stable version from all that came before it and not a rushed testbed for DE that aren't battle-tested.