The 120hz screen increases your perception of the lag because the screen refreshes faste than usual, you see the glaring stutters far more then usual. An iPad Pro 10.5 will seem more stuttery than the 7 Plus despite having the same amount of stutters because of the refresh rate.I kept my 2nd gen Pro 12.9 on iOS 10 because it felt more stuttery than 7 Plus.
Funny. People said the complete opposite when the 10.5” and 2nd Gen 12.9” first came out and said the 120hz hid the stutters.
So which is it? Can’t be both.