A company has an application that posts messages to Amazon SQS. Another application polls the queue and processes the messages in an I/O-intensive operation. The company has a service level agreement (SLA) that specifies the maximum amount of time that can elapse between receiving the messages and responding to the users. Due to an increase in the number of messages, the company has difficulty meeting its SLA consistently. What should a solutions architect do to help improve the application's processing time and ensure it can handle the load at any level?