Starbucks cafes in the United States are implementing changes to improve efficiency and reduce long wait times, with the rollout of the new "Siren Craft System" to streamline drink production. More than 10% of Starbucks stores have already adopted the system, with plans to expand it across North America by the end of July. The changes come as Starbucks anticipates a surge in mobile app orders, aiming to address issues like incomplete orders and declining foot traffic. The company is adding a new role called the "play caller" to help solve bottlenecks in cafes and changing the order in which drinks are made to improve speed and service. Starbucks hopes these initiatives will revitalize its business after a disappointing second quarter. As part of the strategy, Starbucks has also started offering a $5 food and beverage combo option to attract customers and communicate value.