[southpolesteve]

API Gateway needs less config since they released the proxy style integration. In Lambda's case this means you can just return a JSON object like:

{ "statusCode": 200, headers: {}, body: "<h1>Hello!</h1>" }

And API Gateway knows exactly what to do. Before this, yes there was some extra config and it was not fun.

PS. Our AWS bill went down when we moved everything to Lambda but that was not the motivating factor for the switch

[takeda]

Is it possible that perhaps your EC2 instances were bigger than they should be, and perhaps to make Lambda work in satisfactory manner you also placed CloudFront in front of it?

Because those sites you mentioned (bustle.com and romper.com) look like something that could benefit a great deal from using CDN which would then drastically reduce need for large instances.