How does memo, useMemo, useCallback change at 10× traffic?

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Quick interview answer

At 10× traffic, memo, useMemo, useCallback usually hits queueing and CPU/I/O saturation first — mitigate with concurrency limits, batching, caching, and offloading. Logic: React.memo skips re-render if props shallow-equal. useMemo caches computed value; useCallback caches function reference — helps memoized children avoid redundant renders.

Detailed answer

At 10× traffic for memo, useMemo, useCallback: 1) Bottleneck shifts from “works on my laptop” to queue delay and resource saturation. 2) Protect the loop/path: timeouts, bulkheads, backpressure, worker offload for CPU work. 3) Scale out carefully: sticky vs stateless, connection pools, cache hit ratio. 4) Prove with load tests that p99 stays inside SLO. Example to cite: Heavy DataGrid row component wrapped in memo; stable onSort callback via useCallback. Parent context: Logic: React.memo skips re-render if props shallow-equal. useMemo caches computed value; useCallback caches function reference — helps memoized children avoid redundant renders.

Full explanation

Focus on what breaks first and how you keep memo, useMemo, useCallback correct under load. React.memo skips re-render if props shallow-equal. useMemo caches computed value; useCallback caches function reference — helps memoized children avoid redundant renders.

Follow-up questions

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Parent context — memo, useMemo, useCallback

Logic: React.memo skips re-render if props shallow-equal. useMemo caches computed value; useCallback caches function reference — helps memoized children avoid redundant renders.

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