That depends a lot on your application, that said, i'd like to add CloudFront. The more you respond from the CDN cache, the less requests hits your backend and

That depends a lot on your application, that said, i'd like to add CloudFront. The more you respond from the CDN cache, the less requests hits your backend and that can be huge, it is not unusual to offload 80-90% of traffic. When it hits the backend, if it is Lambda functions you can also save a lot by ensuring you don't have wasted resources. Same idea for databases, DynamoDB is very cost effective. Usually the less you manage or provision by hand, the more you save.