Cold starts in serverless environments

WHAT IT TESTS: why the first request to a scaled-from-zero function is slow. ANSWER OUTLINE: a cold start occurs when no warm instance exists, so the platform must allocate a container, load the runtime, import your code and dependencies, and run initialization before handling the request, adding latency to that first call. Mitigations: provisioned or minimum-instance concurrency to keep instances warm, and reducing init cost via smaller deployments, lazy loading, and lighter runtimes. RED FLAG: blaming network or steady-state latency.