[tannhaeuser]

For fast startup, look at GraalVM/native-image which compiles Java to native code and works very well.

Downsides are that highly dynamic and reflection-happy Java code bases/libs won't run OOTB, that using profile-guided optimization (for achieving or surpassing HotSpot perfornance levels) requires a commercial EE license from Oracle (about 300-400 bucks per seat last I checked, not required for mere development until used in prod or at customer sites, and bundled with commercial JRE/JDK subscription since about a year), that even with EE your garbage collector choices are limited, and the somewhat overwhelming number of optimization flags to pass to native-image, not unlike earlier JVM runtime arg excesses.

[mike_hearn]

Although note that using PGO with Go isn't really common either. Actually, JVM languages and JS are amongst the very few that use PGO regularly as setting it up and using it with AOT compiled toolchains takes more work.