Faster jruby startup

One of issue with JRuby and Java in general is long startup time. As the result, a lot of peoples including myself use MRI when developing application and then use JRuby to test and run the application.
Recent change is jruby shell script have improved startup time at significantly by putting JRuby library into java boot classpath (using -Xbootclasspath/a:) instead of normal classpath to bypass java class verification, however it still so slow compare to MRI.
Below is a simple test on machine
1. jruby lib in classpath

huy@huy-desktop:/u01/jruby-1.1.1/bin$ time jruby -e "puts 'hello world'"
hello world

real    0m2.934s
user    0m2.604s
sys     0m0.136s

2. jruby lib in boot classpath

huy@huy-desktop:/u01/jruby-1.1.1/bin$ time jruby -e "puts 'hello world'"
hello world

real    0m1.124s
user    0m0.896s
sys     0m0.072s

3. MRI

huy@huy-desktop:/u01/jruby-1.1.1/bin$ time ruby -e "puts 'hello world'"
hello world

real    0m0.060s
user    0m0.004s
sys     0m0.004s