Another disappointing limitation is being restricted to Node.js. AWS Lambda lets you write your code in Node.js, Python, Java, or C#. This is particularly useful for tuning your Lambdas based on their expected usage. If you have a Lambda that is being constantly invoked, it might be better to write it in Java. It has a longer start up time but has better performance after the initial startup. However, if your Lambda is invoked infrequently (and thus is frequently shutdown from inactivity), it would better to write it in Node.js or Python to take advantage of the snappier start up time.