I've been using YNAB4 with the dropbox cloud sync since it's availability and it has been a great improvement to keep all our devices 100% synchronized. Earlier, we would let things get out of date because of the extra synch steps.
However, I upgraded this morning to 4.1.127 and the desktop app is slow slow as to be unusable. I've got very long delays when typing money amounts (1-2 seconds per keystroke) and the drop downs take a few seconds to appear when approving imported data. after clicking on the (i) icon for the dropdown menu the menu appears like this for about 2 seconds before filling in: