Fast food is all about getting food, well, fast.

So a hungry and impatient fast food customer likely won’t suffer through downloading a large app and clicking through 10 screens to get a burger and fries.

Mobile ordering, when designed right, however, accelerates fast-food purchases. Restaurateurs that want to take their digital ordering to the next level via mobile web or an app, should keep in mind the following tips from digital ordering vendor Olo, which has created apps for fast food brands including Five Guys, Noodles and Company, Fazoli’s, Capriotti’s and Cousins Subs.

First off, the  app must be fast, says Noah Glass, founder and CEO at Olo. Glass recommends that the first page load within two seconds; anything longer than eight seconds is too slow. Restaurants should prioritize speed over a beautiful design and images, he says.

“The more clicks that are involved, the more seconds that are involved, correlates directly with drop-off, with people abandoning their carts,” Glass says.

One way to ensure speed is storing data, such as some images, in the app. This way, the images load right away, as opposed to having the app call the images from the web server and forcing a consumer to wait for them to load.

Having everything saved in app, however, makes the app heavier, and running heavier apps uses up more smartphone memory—which can slow performance of both the app and a consumer’s smartphone. As app creators have access to faster smartphone hardware and the newest versions of mobile operating systems, some developers are tempted to design heavy apps. But experts say it’s important for a developer to realize that not everyone is running the latest mobile operating system or using the newest smartphone model.

To prioritize space, restaurants should think of the most important elements needed in a restaurant app, such as making an order easy to complete, and cut out non-essential items, such as a Welcome and Who We Are page. After all, a user of the restaurant’s app is most likely a loyal customer who already knows such information.

Capriotti’s sandwich shop focused on ordering and loyalty when designing its app. In July 2014, Capriotti’s piloted its first-ever app at a few of its locations.  The restaurant officially rolled it out with all 103 locations in June 2015. It currently has 17,531 downloads on Android and iOS, says Morgan Waldron, digital marketing specialist at Capriotti’s. With the app Capriotti’s also updated its desktop ordering system. The restaurant has a separate mobile web site that it plans to update soon.

One significant improvement Capriotti’s noticed when it updated its desktop ordering system and launched the app is improved order accuracy. Previously, customizing an online order meant a customer had to write his special request in a text box, such as “Please, no mayonnaise on my turkey sub.” The orders are printed out on a receipt at the shop, and if a customer wrote too much in the text box, the sentence was cut off, Waldron says. Now when checking out, a customer is given specific options for customization, so the orders are clear and consistent, Waldron says.

When a consumer downloads the Capriotti’s app, she is automatically enrolled in the loyalty program. The app will alert consumers about promotions and rewards, such as $2 off an order, via a push notification. If she didn’t opt in to push notifications, the offer will show up the next time she opens the app. The more often the consumer purchases, the better the offers get, such as a free sandwich rather than a free drink, Waldron says. 51% of its app customers are repeat buyers, opposed to 21% of desktop customers.

The app and desktop ordering system also halved the number of clicks—from 10 to five—that it takes to order digitally, Waldron says.

Capriotti’s lets its customers know about the app via in-store promotions, social media ads on Facebook and Twitter, plus radio and print advertisements, Waldron says.

Chain restaurants with multiple locations should ensure that when they roll out mobile ordering, it is available at all of its locations, Glass says. If a customer downloads an app because he is a loyal customer and wants to order food from a nearby shop and can’t, it seems to him that the app is broken, Glass says. The same logic holds true for developing apps for both Android and Apple devices.

“A lot of brands pass up Android and I think that is a big mistake,” Glass says.

Cousins Subs is one sandwich chain that until recently only offered online ordering for 70% of its 111 locations, meaning the sandwich shop couldn’t promote the app online on nation-wide advertisements, says Matthew Somoles, director of field services at Cousins Subs. Digital ordering was opt-in for its franchisees, and many shop owners didn’t choose to sign up for it, Somoles says.

Somoles likens digital ordering to the introduction of credit cards. Some businesses tried to be cash-only, but eventually credit cards won, he says. “Same thing with online ordering, it’s here to stay. It’s not a want, it’s a necessity.”

The sandwich chain decided to launch a new website and debut a mobile ordering app, and make digital desktop and app ordering mandatory for all 111 locations by mid-2014. Each restaurant had to buy a  $400 printer for digital orders. Each franchise location also pays a flat monthly fee for using all the digital ordering options from Olo, which on average is $99, Glass says.

Since its June 2014 launch, the app has accumulated 12,169 downloads on both Android and iOS, and sales via its app account for 21% of online sales. Mobile web accounts for 15% and desktop 65%. 77% of app customers repeat an order, compared to 34% repeat customers on mobile web and 35% on desktop. The app’s conversion rate also tops the other digital platforms, at 35%, compared to 12% on mobile web and 30% on desktop. Total web traffic also increased 33% year-over-year between June 2013 and June 2015, Somoles says.

If restaurants want to promote mobile ordering as the fastest way to get food, they should also require customers to pay for their food when they order it, Glass adds. This way, customers don’t have to wait in line to pay at the store.

For Five Guys, another fast food restaurant and client of Olo’s, coupling the order with payment not only saved customers time, it saved the chain money. Each Five Guys location threw out $10,000 worth of food per store annually from consumers placing phone orders and never showing up, Glass says.

Restaurants should also consider having a designated spot in their shops for customers to pick up their digital orders to save those online customers time waiting in line, Glass says.

Follow mobile business journalist April Dahlquist, associate editor, mobile, at Mobile Strategies 360, @Mobile360April

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