Which solution will meet these requirements MOST cost-effectively?

Explanations:

Provisioned concurrency keeps a specified number of Lambda instances warm, reducing cold starts but incurs additional costs for always-on instances, which may not be the most cost-effective solution given the lack of strict latency requirements.

Increasing the timeout of the Lambda functions does not directly impact startup latency or cold starts; it simply allows the function to run longer before timing out, which does not address the underlying issue of latency.

Increasing the memory allocation can improve performance and reduce execution time but does not specifically address cold starts or the latency issues related to scaling up. Moreover, it could lead to higher costs without guaranteed improvements in startup latency.

AWS Lambda SnapStart is designed specifically for Java functions to reduce cold start times significantly by taking a snapshot of the function’s initialization state. This solution is likely to be the most cost-effective in reducing cold starts and latency for Java 11 Lambda functions without incurring continuous costs.