Module Overview: Scaling & Performance Interview Questions

“Design a system that handles 10 million concurrent users.”

This is one of the most common system design interview questions. In this module, you’ll learn how to answer scaling and performance questions confidently.

Interview Questions You’ll Master

• “Design a video streaming platform like YouTube/Netflix”
• “How would you design a system to handle 10M concurrent users?”
• “Design a system with < 200ms latency”
• “How do you ensure high availability (99.99%)?”

What Interviewers Look For

• ✅ Understanding of horizontal vs vertical scaling
• ✅ Ability to estimate capacity and scale
• ✅ Knowledge of performance metrics (latency, throughput)
• ✅ Trade-off analysis (cost vs performance)
• ✅ Clear communication of your design

Goals

• Answer scaling questions with confidence
• Use scale blocks to model auto-scaling strategies
• Define SLOs to show production-ready thinking
• Explain trade-offs clearly to interviewers

Interview Framework

We’ll follow this approach for each question:

1. Clarify Requirements - Ask about scale, latency, availability
2. Design High-Level - Start with core components
3. Model with Sruja - Visualize your architecture
4. Discuss Scaling - Show how it handles load
5. Optimize - Improve based on constraints

Estimated Time

60-75 minutes (includes practice)

Checklist

• Understand how to approach scaling questions
• Model scaling strategies with Sruja
• Define SLOs to show production thinking
• Practice explaining trade-offs clearly