About the lag you're getting, appears that FLY is fighting for power used by other apps running on your device. Should improve by shutting down other power intensive apps running in background during your fights.
Wind , that is a very light drone and without direct input is going to move with the wind more than most.
Its not as bad as if you flying it directly forward but just coming down like that its a feather .
Phantomrain.org
Gear to fly your Mini 4K...