Optimize performance of Node / AWS API serving a high-traffic web app

The API in question serves our web app, which is available at www.pixton.com. It’s a single Nodejs / Express / Serverless function running on AWS Lambda / API Gateway.

The API makes use of numerous AWS services, including RDS (Aurora serverless), Elasticache (Redis), DynamoDb, S3 / Cloudfront.

In anticipation of increased traffic to our web app, which currently gets a million logins per month, we’d like to increase performance. For instance, data currently caced in Redis should probably be moved to DynamoDb.

The API brings together two distinct coding efforts, so some refactoring would also be good, to make the entire code base consistent.