I have a 2018 iPad Pro and I am also experiencing these slowness issues. A note-taking app should not be so slow on such a powerful device. I do have a number of notes and I excerpt out of books so some of the notes can contain much text, but the computing power inside a 2018 iPad Pro is enormous.
Combined with other bugs (old and new), I am seriously considering switching to something else which works across iOS and Windows. As best I can tell, Evernote spends most of its developer time on large businesses, and so their concerns matter much more than ours.