> the same class. In my tests rbtree is better for deleting elements but
> worse than a Hash for inserting them.

Since we are talking about performance benchmarks too, Ruby 1.9's
ordered hashes also exhibit faster reads than writes.

[1]: http://www.igvita.com/2009/02/04/ruby-19-internals-ordered-hash/

-- 
Anurag Priyam
http://about.me/yeban/