Actually, I see the same notification issue in Facebook. I don't think I ever login to Facebook without my immediate number of notifications being exactly 1 mo

Actually, I see the same notification issue in Facebook. I don't think I ever login to Facebook without my immediate number of notifications being exactly 1 more than they should. The last "new" notification is always what I have already most recently checked. So in this sense, Facebook is also very fast, and also does not have an entirely flawless system.