An e-commerce company operates an application on AWS, utilizing Amazon API Gateway to invoke AWS Lambda functions. The application's data is managed in an Amazon RDS for PostgreSQL database instance. During a recent flash sale event, the application experienced degraded performance due to a surge in API calls. Upon reviewing Amazon CloudWatch metrics, a solutions architect identified a sharp rise in Lambda invocations, database connections, and high CPU utilization on the DB instance. What measures should the solutions architect propose to enhance the application's performance under such high-traffic conditions?