A development team has an Amazon API Gateway REST API that is backed by an AWS Lambda function. Users have reported performance issues for the Lambda function. The development team identified the sour

Reserved concurrency sets a maximum concurrent execution limit for the function to prevent throttling of other functions, but it does not pre-warm instances or eliminate cold start initialization time.

Increasing the function timeout extends the maximum allowed execution duration but has no effect on the initialization phase that causes cold start latency.

Increasing memory provides proportionally more CPU, which can shorten initialization slightly, but it does not pre-initialize execution environments and cannot eliminate cold starts the way provisioned concurrency does.

Provisioned concurrency pre-initializes a configurable number of Lambda execution environments so they remain in a ready-to-invoke state at all times. Unlike on-demand invocations that incur a cold start initialization period, provisioned concurrency guarantees that the runtime, dependencies, and initialization code are already loaded, delivering consistently low-latency responses to API Gateway requests.