You have to remove the cylinder to load or unload. To remove the cylinder, you just need to pull the cylinder pin out the front, take the cylinder out and stuff rounds into it, then replace the cylinder and pin. I suppose a minute or so to load... Same for unloading except you use the pin to manually push the spent brass out of the cylinder one at a time. adds an extra 20 seconds maybe; at most. Not really bad, just not as quick as most revolvers.
Although that said, single action revolvers of any type can be painfully slow to load and reload. I'd say the NAA guns are still quicker to load/unload than your average single action revolver
with a single loading gate.