One thing that could certainly help is moving to a apache/nginx +
passenger setup. That would improve your memory usage.
But keep in mind that if you rely on ruby threads on your application,
ruby won't take advantage of your QuadCore processor. Only if you
spawn multiple processes. But again, this depends on your application
and how it works.
That being said, I wrote a post a whlie ago explaining a bit how ruby
handles threads (in 1.8, 1.9 and in jruby). It might be useful as