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Performance Engineering and Cost Optimization Questions

Engineering practices and trade offs for meeting performance objectives while controlling operational cost. Topics include setting latency and throughput targets and latency budgets; benchmarking profiling and tuning across application database and infrastructure layers; memory compute serialization and batching optimizations; asynchronous processing and workload shaping; capacity estimation and right sizing for compute and storage to reduce cost; understanding cost drivers in cloud environments including network egress and storage tiering; trade offs between real time and batch processing; and monitoring to detect and prevent performance regressions. Candidates should describe measurement driven approaches to optimization and be able to justify trade offs between cost complexity and user experience.

HardSystem Design
0 practiced
Architect a system that supports ad-hoc analytics queries with sub-500ms latency for interactive dashboards while also running full nightly aggregations. Propose a hybrid architecture that balances cost and freshness and explain the trade-offs.
MediumTechnical
0 practiced
A mobile client tolerates some staleness. Propose a design to deliver a news feed that balances freshness and cost. Include caching, background refresh, prefetching, and how you would measure the marginal UX improvement vs incremental cost.
MediumTechnical
0 practiced
Design a distributed cache invalidation strategy to minimize stale reads for a multi-region service. Consider TTLs, explicit invalidation, versioned keys, pubsub-based invalidation, and the risk of race conditions or partial invalidation.
MediumSystem Design
0 practiced
Design a load test plan to validate an API that must support 100k RPS with p95 latency under 200ms. Include test tooling choices, how you will generate realistic traffic (auth, session behavior), data setup, warmup, and how to run stress vs soak tests.
MediumTechnical
0 practiced
Describe how you would configure a realistic distributed load test using tools like Locust, Gatling, or k6 to model sessions with think-times, authenticated flows, and background data warm-up. Explain how to collect and interpret percentiles and error budgets from the test.

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