You are probably thinking about Nokogiri.
I have not used it myself, but "everyone" is talking about it and the benchmarks do look interesting:
hpricot:html:doc 48.930000 3.640000 52.570000 ( 52.900035)
hpricot2:html:doc 4.500000 0.020000 4.520000 ( 4.518984)
nokogiri:html:doc 3.640000 0.130000 3.770000 ( 3.770642)
