speedup launch without nailgun

[cvogt]

@rockjam's recent changes have gotten cbt's own startup times down to ~0.6 seconds for me. (The launch via a hot nailgun takes ~0.1).

The advantage without nailgun is that there is no global state and forking the JVM for runs will be less relevant.

We might want try even more performance tweaks here. I can see us profiling more with VisualVM but also trying to tweak the java flag mots. Here is what sbt-extras uses: exec java -XX:+UseConcMarkSweepGC -Xms512M -Xmx1536M -Xss4M -XX:+CMSClassUnloadingEnabled -XX:ReservedCodeCacheSize=256M ...

[cvogt]

This is not a priority for me personally, but I assume @rockjam or someone may wanna work on this.

[cvogt]

also see https://gitter.im/cvogt/cbt?at=57ff736f457ae29b71d6a11a

[tim-zh]

Looks like https://github.com/gradle/gradle doesn't use special JVM args at all. And everybody is happy with it.

[cvogt]

this might help analyze the startup: http://cr.openjdk.java.net/~redestad/bytestacks/bytecode-startup-analysis.html