Most people don't buy a jar of relish every week. But when they decide to buy one from Ocado--the world's largest online-only grocery retailer--they don't have to scrabble at the back of the store. Instead, they call on robots and artificial intelligence to have it delivered to their door.

Ocado claims that its 350,000-square-foot warehouse in Dorden, near the U.K.'s second city of Birmingham, is more heavily automated than Amazon's warehouse facilities. The company's task is certainly more challenging in many respects: most of the 48,000 lines of goods that it sells are perishable, and many must be chilled or frozen. Some, such as sushi, must be delivered on the same day they arrive in the warehouse.

That turns storing, picking, and shipping items into a complex, time-constrained optimization problem. But in order for Ocado to grow and turn a profit--which it does, despite a crowded U.K. grocery market--it has to make every step as efficient as possible.

Currently, when a customer orders groceries via Ocado's website, large plastic crates are swiftly filled. The containers are packed by hand, but little legwork is required: 30 kilometers of conveyor belts at the Dorden warehouse carry empty boxes straight to people who work as pickers. They grab items from shelves that are replenished by robots, or from boxes brought out of storage via cranes and conveyors. Ocado's algorithms monitor demand for products and use the information to map out an optimal storage scheme, so that popular items are always within easy reach.

Once an order is packed, it's hauled off in a large truck and taken to a distribution center to be loaded into a van. Each van then embarks on a delivery route that can be carefully optimized according to factors such as customer time preferences, traffic, and even weather.

But Ocado wants to be faster. "Fractions of a second in our business count," says Paul Clarke, Ocado's chief technology officer. "It's all about how we can shave the next little bit off our process."