Scalability and Performance Optimization Questions

Evaluates how a candidate measures, diagnoses and resolves performance and scalability challenges across the stack. Candidates should explain instrumentation and profiling approaches, define performance metrics such as latency and throughput, and present concrete before and after numbers for optimizations. Topics include caching strategies at different layers, database indexing and query optimization, denormalization trade offs, batching and asynchronous processing, efficient network usage and serialization, connection management and pooling, load balancing and horizontal scaling, partitioning and sharding strategies, client side optimizations such as asset bundling and lazy loading, and techniques for load testing and capacity planning. Interviewers expect discussion of trade offs, cost implications and how changes were validated in production.