I started with the obvious stuff like caching and CDNs and the interviewer just kind of waited.
Structure your answer by first clarifying the scope (e.g., frontend, backend, network) and then systematically covering the request lifecycle from client to server and back. Emphasize trade-offs and prioritization based on metrics and user impact, as expected in a system design context.
Pro tip: Demonstrate maturity by discussing how you would measure and monitor latency (e.g., percentiles, RUM) and iterate on optimizations, rather than just listing techniques. This shows a data-driven approach and awareness of real-world constraints.
Ask clarifying questions to understand the context: is this for a new or existing site? What are the current metrics and user expectations? This ensures your answer is targeted and relevant.
Break down the journey of a request: DNS, TCP/TLS, server processing, database, and rendering. Identifying each stage helps systematically address latency sources.
For each stage, list potential improvements such as caching, CDNs, code optimization, and database indexing. Prioritize based on impact and effort.
Explain how choices like caching introduce complexity or consistency issues. Show awareness of balancing latency with cost, scalability, and maintainability.
Emphasize the importance of monitoring tools (e.g., Lighthouse, tracing) to validate improvements and guide further optimizations.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.