Nailgun in trunk shows little or marginal improvement for most Rails test suites

using the --ng switch w/running server gives marginal performance improvement over straight jruby. Submitting this ticket @ the request of headius.

Chat from #jruby:

01:05 < headius> STAT!
01:05 < headius> goddamn stat
01:05 < headius> that UnixFileSystem.canonicalize has been a thorn in our side
forever
01:05 < headius> it's so slow
01:06 < headius> Can you paste that section into a bug describing your perf
issues?

profiler dump w/ -Xprof switch (http://www.pastie.org/479886):

Stub + native Method
28.5% 0 + 2305 java.io.UnixFileSystem.canonicalize0
10.5% 0 + 850 java.lang.String.intern
2.5% 0 + 202 java.lang.Class.isArray
1.8% 23 + 123 java.security.AccessController.doPrivileged
1.4% 0 + 113 java.io.UnixFileSystem.getBooleanAttributes0
1.0% 0 + 83 java.lang.ClassLoader.findLoadedClass0
0.7% 0 + 60 java.util.zip.ZipFile.getEntry
0.2% 16 + 4 java.security.AccessController.doPrivileged
0.1% 3 + 7 java.security.AccessController.doPrivileged
0.1% 0 + 9 java.lang.Class.isPrimitive
0.1% 0 + 8 java.lang.System.identityHashCode
0.0% 0 + 1 sun.reflect.Reflection.getCallerClass
47.1% 42 + 3765 Total stub