From launching Dashbird one and a half years ago, our team has been in contact with a lot of companies building serverless applications and one of the problem areas that keeps poppping up are performance or cost issues. Performance problems usually present themselves when some best practices are overlooked or a suboptimal architecture decision have been made. This article is focused on how to look for optimization opportunities and to capitalise on those opportunities.

While serverless applications usually consist of event sources, lambdas functions and external services, functions almost always present the most opportunity for optimization. Mainly because as a developer, you have less control over (managed) event sources and external services. To spot opportunities for efficiency, lets look under the hood for a second and identify where we should look.

Anatomy of a Lambda function

Breaking a Lambda function into pieces you can see there are multiple places to look for optimizations.

• Your function code is usually the biggest opportunity for optimization and a threat of making mistakes.
• Language runtime, Python, Go binary Node.js etc. does not allow optimization.
• Execution environment is a somewhat unintuitive place to think about but it can have an effect on performance. For example, how an function is invoked, is it in VPC and needs an ENI? Are there too many redundant packages?
• Compute substrate also allows no optimization. AWS controls this and there’s nothing you can do about this.

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