We now use Zappa only for packaging the ZIP that we upload to Lambda. For deployment, we use CloudFormation (via Sceptre) which we've found to be a much more robust, declarative approach than Zappa's imperative-style deployment.
We use Lambda primarily to improve developer efficiency and to allow dev teams to own their own operations end-to-end, with cost efficiency only a secondary goal. It's been great for that as it's a small enough thing to integrate with that any given developer can learn the entire operations stack (for their team's services) well enough to work on it themselves.
3 seconds on cold request sounds unusual, it should be around a second or less - have you measured it? If you use VPC you'll unfortunately be in the realm of 20-30 seconds cold start, which is why we've avoided it for Lambda (and used stores like DynamoDB rather than RDS which work with IAM as an alternative to security groups). No Elasticache without VPC is going to be a big problem soon though...
We use Lambda primarily to improve developer efficiency and to allow dev teams to own their own operations end-to-end, with cost efficiency only a secondary goal. It's been great for that as it's a small enough thing to integrate with that any given developer can learn the entire operations stack (for their team's services) well enough to work on it themselves.
3 seconds on cold request sounds unusual, it should be around a second or less - have you measured it? If you use VPC you'll unfortunately be in the realm of 20-30 seconds cold start, which is why we've avoided it for Lambda (and used stores like DynamoDB rather than RDS which work with IAM as an alternative to security groups). No Elasticache without VPC is going to be a big problem soon though...