The author doesn't state the Java version but more recent version JREs (9+ IIRC) start up way faster than older versions. I'd imagine a JRE's launch time is hea

The author doesn't state the Java version but more recent version JREs (9+ IIRC) start up way faster than older versions. I'd imagine a JRE's launch time is heavily influenced by disk cache. A warm launch ends up way faster than a cold launch with the tens of megabytes of classes in RAM means the warm launch basically loads the program's class file from disk.