Cloud cost is a first-class architectural concern. A great .NET architect doesn't just build fast apps; they build Cost-Efficient apps.
If you know you'll be using EC2 or Fargate for the next year, don't pay the 'On-Demand' price. Commit to a **Compute Savings Plan** and save up to 72% instantly. It's the easiest way to slash your bill without changing code.
Use **AWS Compute Optimizer**. It analyzes your CloudWatch metrics and tells you if your .NET instances are over-provisioned. If your M5.large is only using 5% CPU, move it to a T3.medium. Architecture is about efficiency.
The 'Silent Killer'. Transferring data between AWS Regions or out to the public internet is expensive. **Solution:** Use **CloudFront** (which has lower data-out rates) and keep your traffic within the same Availability Zone whenever possible by using **VPC Endpoints**.
Q: "How do I implement developer accountability for costs?"
Architect Answer: "Use **Tagging**. Every resource must have a 'CostCenter' and 'Project' tag. You can then use **AWS Cost Explorer** to see exactly which team is spending the most money and why. Visibility is the best driver for responsible architecture."