I am trying to develop a AWS lambda function which is triggered when a file shows up in a specific s3 bucket. I am trying to follow the examples from AWS Lambda developer guide, using aws-java-sdk-... More on github.com

update aws lambda java libs to aws sdk java v2 (https://github.com/aws/aws-sdk-java-v2) More on github.com

Very often the best language for a team/org is not the "best" language for particular component. If it's a Java based team it often doesn't make sense to dump all that investment just for Lambda if Java performance there is acceptable. Personally I won't use Node for anything if I can possibly avoid it. If Python isn't fast enough and in particular if threading will help I'll use Go. But even as anti-Node as I admit I am, I absolutely respect that in shops with a lot of Javascript talent due to frontend work it often makes the most sense to go with Node for backend work despite its many hair pulling issues. It's much better to be pragmatic than "right". Lambda supports a ton of languages (effectively all of them if we count custom runtimes) because it's pragmatic. More on reddit.com

I’ll echo the sentiment of others here and say that a 3 second cold start is way outside the normal range I observe. Virtually all my lambdas in recent memory have cold starts under 200ms. In my case these are NodeJS lambdas deployed by CDK, using esbuild under the covers. They are small and start fast. Are you doing a lot of work outside the handler during init or something? If you are fetching parameter store values or similar in your init outside the handler then that may require more time. This extra overhead will be present regardless of language selection. More on reddit.com