An online shopping application accesses an Amazon RDS Multi-AZ DB instance. Database performance is slowing down the application. After upgrading to the next-ge...

An online shopping application accesses an Amazon RDS Multi-AZ DB instance. Database performance is slowing down the application. After upgrading to the next-generation instance type, there was no significant performance improvement.
Analysis shows approximately 700 IOPS are sustained, common queries run for long durations and memory utilization is high.
Which application change should a solutions architect recommend to resolve these issues?