Most restaurants I have a drive through either have one person taking orders and one person doing handout, or a person that can take orders and do handouts at the same time.
The Krispy Kreme method, no matter how long of a line there is, is to take one order let that person mosey up to the window and then completely handle their order while making everyone else it back in line at the ordertaking station.
If you are in any kind of hurry at all, and you even see one car pull in to the drive through and front of you, the best thing for you to do is do a U-turn and go to the quick trip down the street to get your donuts. You'll be sitting there for 15, 20, even 30 minutes waiting for your order while they slowly service the people in front of you. I've learned this the hard way on three different occasions. Now I only stop there if there are no cars in the drive-through. If there's a car or a line, you're going to spend a long time waiting for your Krispy Kreme donuts. Very slow service.