When using the DayZ alternate or "new" control scheme in the General tab, your aim down sight is delayed.

Going from hip fire to aim down sight takes longer.
I noticed immediately upon switching.

It is because ads activates not when the right stick is pressed, but when you release it. You can see this if you hold the right stick down for just slight delay then let go. And you will see that the ads is activating when the button is released. On the default control scheme this issue isn't present.