How do you reduce cold start latency in serverless functions?

Cold start reduction strategies: (1) Provisioned Concurrency (AWS Lambda) — pre-warms a specified number of execution environments, guaranteeing zero cold starts for that concurrency level. Costs additional ~15% over standard pricing; (2) Minimize package size — smaller packages download and initialize faster. Tree-shake unused code, exclude dev dependencies, use Lambda Layers; (3) Choose a faster runtime — Node.js and Python have significantly faster cold starts than Java or .NET (JVM startup is expensive); Go and Rust compile to native binaries with minimal startup; (4) Avoid heavy initialization in handler — database connections, SDK clients, and config loading should happen in the module scope (outside the handler), cached between invocations on warm containers; (5) Lambda SnapStart (Java) — takes a snapshot of initialized Lambda state (after the @BeforeCheckpoint hook), restoring from snapshot instead of initializing from scratch; (6) Reduce memory footprint — less memory to initialize means faster cold starts; (7) Scheduled warming — ping functions every 5 minutes with a dummy request to keep containers warm.