Lambda functions initialize in <10ms when warm, <100ms otherwise, in my experience. They seem to stay warm for 15 minutes or so after a cold start. The excelle

Lambda functions initialize in <10ms when warm, <100ms otherwise, in my experience. They seem to stay warm for 15 minutes or so after a cold start. The excellent Serverless framework is pure JS, but you can also deploy jars to Lambda, which lets you use any JVM language. Clojure Lambdas have a more extreme profile: ~500ms for a cold start, <1ms once warm. You could keep it warm with a timer event source, which could do double duty as a watchdog / heartbeat thing.