I have an iPhone X and the app switched over to the UI earlier this week. I'm seeing the same slow performance that is outlined in this thread. For example, I'll go to a note and have to wait 10-15 seconds for the note details to show up.
Also, it seems searching within a note is broken. I'll search for a term, and I can see the term highlighted in the note, but it's not showing up in the results.
This is not the user experience I expect for an app I am paying for.