Cold starts for .NET applications on AWS Lambda are often overstated as a concern. A cold start occurs when a new execution environment is created for the first invocation, involving downloading the app, allocating memory, JIT compilation, and running initialization code. Warm environments reuse existing instances and skip initialization. Many scenarios exist where cold starts are negligible — infrequent invocations, non-time-sensitive responses, or steady request rates. When cold starts are a real problem (e.g., unpredictable bursts requiring fast responses), mitigation options include provisioned concurrency, combining functions, prewarming, reducing binary size, adding memory, using ReadyToRun or native AoT compilation, and targeting arm64 architecture.
