How should a developer modify the application to improve performance?

Explanations:

Using Amazon ElastiCache to cache query results would significantly reduce the number of read requests sent to the RDS instance, thus improving performance during peak times. Caching frequently accessed data can lower the read latency by serving cached data quickly instead of querying the database directly.

Scaling the ECS cluster to add more instances may help distribute the load of the application, but it does not address the underlying issue of high read latency on the database. If the bottleneck is with the database read performance, simply adding more ECS instances will not resolve the performance degradation.

Adding read capacity units (RCUs) is relevant to Amazon DynamoDB, not Amazon RDS for MySQL. Since the application is using RDS, this option is not applicable. Additionally, RDS performance can be improved through other methods, such as read replicas, rather than RCUs.

Modifying the ECS task definition to increase task memory may enhance the performance of the application itself, but it does not directly impact the database’s read latency. The issue at hand is related to the database’s capacity to handle read requests, which is not resolved by increasing memory for the ECS tasks.