Maybe you should try using the 3-finger drag option (Accessibility → Pointer Control → Trackpad Options). I'm using that and it doesn't suffer from this delay i

Maybe you should try using the 3-finger drag option (Accessibility → Pointer Control → Trackpad Options). I'm using that and it doesn't suffer from this delay issue, because when the number of fingers on the trackpad changes the system knows that the drag gesture was finished.