As of 1.2.0 DBC for C is using the String Scanner library (http://i.loveruby.net/en/prog/), which is included in Ruby 1.8+. This has result in 50%+ speed up 
All the major changes/fixes are listed on the wiki: http://dbc.rubyforge.org/wiki/wiki.pl?
Source package and Ruby Gem are available.
-Charlie