---
title: "Cost, performance, and sustainability"
chapter: "15"
---

# Cost, performance, and sustainability

The goal is not the smallest bill. It is the required outcome with the least
waste and acceptable risk.

## Main cost drivers

Count EKS cluster fees, extended-support fees, EC2 or Fargate compute, EBS/EFS,
load balancers, NAT processing, cross-AZ and internet transfer, logs, metrics,
security tools, support, and engineer time.

## Reduce waste

- Right-size requests with measurements.
- Use HPA plus Karpenter, Auto Mode, or node scaling intentionally.
- Keep stable baseline on appropriate On-Demand or Savings Plans.
- Use diversified Spot for interruption-tolerant capacity.
- Evaluate Graviton and efficient images.
- Remove idle clusters, load balancers, volumes, snapshots, and ECR images.
- Use VPC endpoints and locality when they reduce unnecessary transfer/NAT cost.
- Control log retention, metric cardinality, and trace sampling.

## Performance

Measure latency percentiles, throughput, errors, saturation, scheduling delay,
image pull time, DNS, database connections, and dependency latency. Load-test
autoscaling and recovery, not only steady state.

## Unit economics

Tag and allocate by owner, environment, application, and cost center. Track
cost per order, user, tenant, build, or request. A growing bill may be healthy
when unit cost falls and business volume grows.

## Feynman check

A half-empty bus may look cheap, but cost per passenger is high. Good platform
economics packs work safely without making one crowded bus a single failure.