Instiq
Chapter 3 · Continuous Improvement for Existing Solutions·v2.1.0·Updated 6/28/2026·~11 min

What's changed: Service coverage: added a catalog section (s4) for developer tools and operations management (CI/CD, Grafana/Prometheus, Proton, Amplify/Device Farm)

3.2Performance and Cost Optimization

Key points

Understand optimizing existing workloads—right-sizing, purchase options (On-Demand/RI/Savings Plans/Spot), Compute Optimizer/Cost Explorer/Budgets/Trusted Advisor, and CloudFront/caching. Keep performance while cutting waste.

Cost optimization rests on right-sizing and choosing purchase options. Boost performance with caching and content delivery.

3.2.1Cost and performance optimization

Diagram organizing cost optimization: purchase options—steady-state = Savings Plans/Reserved Instances (max discount with commitment), variable = On-Demand, interruption-tolerant batch = Spot Instances (max discount, can be interrupted); Compute Optimizer recommends right-sizing; Cost Explorer visualizes spend, Budgets sends budget alerts, Trusted Advisor checks for optimizations; and for performance, CloudFront (CDN) and ElastiCache reduce latency and origin load.
Cost and performance optimization
  • Purchase options: steady = Savings Plans/RI (commit for discount), variable = On-Demand, interruption-OK batch = Spot (max discount).
  • Right-sizing: Compute Optimizer detects over/under-provisioned resources and recommends sizes.
  • Cost visibility: Cost Explorer (analysis), Budgets (alerts), Trusted Advisor (optimization checks).
  • Performance: CloudFront (CDN) for edge delivery, ElastiCache to offload the DB and cut latency.
Exam point

Common on SAP-C02: discount for always-on = Savings Plans/RI, cheapest interruption-tolerant batch = Spot, sizing recommendations = Compute Optimizer, spend analysis = Cost Explorer / budget alerts = Budgets, delivery acceleration = CloudFront. Use commitment plans for steady load, Spot for burst batch.

Tip

Spot can be interrupted, so it suits stateless, checkpointable workloads. A classic mix covers steady always-on with Savings Plans and absorbs overflow with On-Demand.

SAP-C02 probes the fine distinctions between purchase options. Savings Plans commit to an hourly spend ($/h) for 1–3 years: Compute Savings Plans apply automatically across instance family, region, and OS—and even Fargate/Lambda—while EC2 Instance Savings Plans are limited to a family but offer a deeper discount. Reserved Instances (RIs) split into zonal RIs (with a capacity reservation) and flexible regional RIs (no capacity guarantee). Spot gives a 2-minute interruption notice and can pre-empt evictions via capacity rebalancing; an EC2 Auto Scaling mixed-instances policy blends On-Demand/RI/Spot to balance availability and cost. On the visibility side, Cost Explorer surfaces RI/Savings Plans purchase recommendations plus coverage/utilization, Budgets alerts on cost, usage, or RI utilization, and Trusted Advisor runs cross-cutting checks for idle and underutilized resources.

Demand patternBest purchase optionWhy
Steady for 1–3 yrsSavings Plans / RIDeepest discount via commitment
Short-term / unpredictableOn-DemandNo commitment, instant flex
Interruption-OK batch/CISpotMax discount, 2-min interruption notice
Dedicated for licensing/complianceDedicated HostsDedicated physical host, BYOL
Note

Scenario: A steady always-on web tier coexists with large nightly video encoding (interruption-OK). Minimize cost. → Cover the web tier with Compute Savings Plans so it follows family changes; run encoding on Spot in an Auto Scaling group with a mixed-instances policy; set a monthly cap alert with Budgets; and periodically right-size the web tier with Compute Optimizer.

Note

FAQ: Savings Plans or RIs? For flexibility, Compute Savings Plans (auto-apply across family/region/OS, covering Fargate/Lambda). If you need a capacity reservation in a specific family, use a zonal RI. Discounts are broadly comparable, and Savings Plans are generally recommended today.

Warning

Exam trap: Choosing Spot to cheapen a "stateful, can-not-be-interrupted production database" is wrong—an interruption can lose state. Steady workloads call for Savings Plans/RI; Spot assumes interruption tolerance.

3.2.2Section summary

  • Purchase = Savings Plans/RI (steady) / On-Demand (variable) / Spot (interruptible)
  • Visibility = Cost Explorer/Budgets/Trusted Advisor; performance = CloudFront/ElastiCache

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Quick check

(just a quick review)

Q1. You want maximum savings on compute for a production workload running steadily for 3 years. What?

Q2. You want to run large interruption-tolerant batch jobs at the lowest possible cost. What?

Q3. You want analysis of whether EC2/EBS are over-provisioned, with right-size recommendations. What?

Check your understandingPractice questions for Chapter 3: Continuous Improvement for Existing Solutions