Me and my wife have both independently been experience this exact issue. I find myself very often going to write a quick note and it freezes or takes forever to allow me to do anything in the app. I end up just opening up my apple Notes app or OmniFocus to take a note.
I have attempted to download all notes to offline and it doesn't speed it up. I have tried reinstalling the app, same issue.
I don't recall this app being this.... bad. It's getting to be unusable for me. After reading this thread at least I know I am not the only one having this issue.
Does EverNote even recognize this issue? Are they working on a fix?