You may want to check if you're using the server JVM vs. the client JVM also... one of the differences is the level of optimization that the VM tries to do. The server JVM does deeper analysis during classloading, which increases startup to,e. If you have very short running processes (which I'm assuming you do if you're concerned with startup time) the client JVM may be more appropriate.

Also in general, the vanilla JVM startup is pretty quick... the slowness you're experiencing is probably "userspace" code.