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2627 questions of the kind that actually get asked — in interviews, in architecture review boards, and by the person who has to run the thing at 3 AM. Every answer states the trade-off rather than the slogan, and says when the obvious choice is the wrong one.

All areas2627 Architecture Fundamentals81 Distributed Systems101 Data Architecture90 Cloud Architecture77 Networking86 API & Integration Architecture78 Reliability & Resilience88 Observability81 Performance & Capacity Engineering90 Security Architecture85 Cost Architecture & FinOps82 Business Architecture93 Architecture Communication91 Enterprise Architecture91 Legacy Modernization82 AI-Era Architecture86 Software Architecture & Engineering84 Architecture Patterns84 Architecture Decision-Making91 The Architect's Meta-Skills92 Delivery & Release Engineering93 Platform Engineering & Developer Experience92 Testing & Quality Architecture90 Data Platform Architecture88 Streaming & Real-Time Data93 Data Governance & Semantics81 Frontend & Experience Architecture91 Edge, Mobile & IoT88 Regulatory & Data Protection Architecture90 Assurance, Audit & Model Risk88
Difficulty Any beginner intermediate advanced

33 questions in Performance & Capacity.

  1. Little's Law intermediate Multiple choice

    An API platform has an average of 400 requests in flight and processes 2,000 requests per second. What is the average latency, and how is Little's Law used for capacity decisions?

    2 min answer littles-lawconcurrencycapacityconnection-pools
  2. Load Testing intermediate

    A load test passed at 3x expected traffic and production fell over at 1.2x. Name four ways the test could have been unrealistic.

    2 min answer load-testingrealismdatacache
  3. Network Performance Tuning intermediate

    What happens when a load balancer closes idle connections after 60 seconds while the client's connection pool keeps them for 5 minutes?

    3 min answer keep-aliveidle-timeoutconnection-resetnat
  4. Performance Budgets intermediate

    A design platform's web application has grown steadily slower with no single change responsible. What mechanism prevents this, and how should it be enforced?

    2 min answer performance-budgetsciregressionfrontend
  5. Performance Budgets intermediate

    A web experience for low-end devices on slow networks keeps regressing despite good intentions. What mechanism prevents this, and what must it measure?

    2 min answer physics-wallahperformance-budgetmobileregression
  6. Performance Budgets intermediate

    What does a latency budget give you that a latency target does not?

    2 min answer latency-budgetallocationregressionci
  7. Performance Budgets intermediate

    What is a performance budget, why do most attempts at one fail, and how should it be enforced so it actually constrains behaviour?

    2 min answer performance-budgetsregressionciratchet
  8. Performance & Capacity intermediate

    A search engine holds its index entirely in memory to guarantee predictable latency. What does that buy, what does it cost, and when is it the wrong choice?

    2 min answer typesensemeilisearchin-memorypredictability
  9. Performance & Capacity intermediate

    Peak trading day is six weeks away and expected to be four times normal traffic. What do you do in those six weeks?

    3 min answer capacityload-testingpeakreadiness
  10. Performance & Capacity intermediate

    Precompute every user's timeline at write time, or assemble it at read time? Explain why the answer for a social feed is neither.

    2 min answer case-studytwitterfan-outpower-law
  11. Performance & Capacity intermediate

    Your system handles 1,000 requests per second today. Marketing says a campaign will bring 10,000 next month. What breaks first, and how do you find out?

    2 min answer capacitybottleneckload-testingscaling
  12. Profiling & Optimisation intermediate Multiple choice

    A colleague spent a week optimising a function and the endpoint is 2% faster. What went wrong in the approach?

    2 min answer optimisationamdahlprofilingmethod