I believe that startup time is already a solved problem
https://github.com/facebook/nailgun
There is also https://mail.openjdk.java.net/pipermail/discuss/2020-April/0...
There is also https://mail.openjdk.java.net/pipermail/discuss/2020-April/0...
nailgun doesn't solve it generally.
leyden is not released yet; its proposal into JDK future is validation of the approaches projects like GraalVM/Mandrel and Quarkus are doing.