benchmark.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'open-uri'
require 'hpricot'
require 'nokogiri'
require 'benchmark'

uri = URI.parse('http://static.bezurk.com/fragments/wikitravel/sin.xml')
content = uri.read

N = 1000

Benchmark.bm do |x|
  x.report('hpricot:doc') do
    N.times do
      Hpricot.XML(content)
    end
  end

  x.report('nokogiri:doc') do
    N.times do
      Nokogiri::XML(content)
    end
  end
end

Benchmark.bm do |x|
  x.report('hpricot:xpath') do
    N.times do
      doc = Hpricot.XML(content)
      info = doc.search('//location/info').first.inner_text
      url = doc.search('//location/refUrl').first.inner_text
    end
  end

  x.report('nokogiri:xpath') do
    N.times do
      doc = Nokogiri::XML(content)
      info = doc.xpath('//location/info').first.inner_text
      url = doc.xpath('//location/refUrl').first.inner_text
    end
  end
end

Benchmark.bm do |x|
  x.report('hpricot:css') do
    N.times do
      doc = Hpricot.XML(content)
      info = doc.search('location info').first.inner_text
      url = doc.search('location refUrl').first.inner_text
    end
  end

  x.report('nokogiri:css') do
    N.times do
      doc = Nokogiri::XML(content)
      info = doc.search('location info').first.inner_text
      url = doc.search('location refUrl').first.inner_text
    end
  end
end

Result

$ ./hpricot_vs_nokogiri.rb 
      user     system      total        real
hpricot:doc  0.230000   0.010000   0.240000 (  0.265904)
nokogiri:doc  0.030000   0.010000   0.040000 (  0.041641)
      user     system      total        real
hpricot:xpath  1.050000   0.020000   1.070000 (  1.114454)
nokogiri:xpath  0.210000   0.010000   0.220000 (  0.226418)
      user     system      total        real
hpricot:css  1.140000   0.030000   1.170000 (  1.339635)
nokogiri:css  0.700000   0.010000   0.710000 (  0.835559)

Summary

Use Nokogiri's XPath selectors for fastest speed - CSS-based search is faster than Hpricot but not as fast.

Also take note that this benchmark is only shows parsing of XML (not HTML).