diff --git a/app/models/emoji.rb b/app/models/emoji.rb
index 10313e4a45b..4d695f09ff7 100644
--- a/app/models/emoji.rb
+++ b/app/models/emoji.rb
@@ -118,4 +118,16 @@ class Emoji
     "#{Discourse.base_uri}/uploads/#{db}/_emoji"
   end
 
+  def self.unicode_replacements
+    @unicode_replacements ||= Hash[db.map {|e| [e['emoji'], e['aliases'][0]] }]
+  end
+
+  def self.unicode_regexp
+    @unicode_regexp ||= Regexp.union(unicode_replacements.keys)
+  end
+
+  def self.sub_unicode!(text)
+    text.gsub!(unicode_regexp) {|m| ":#{unicode_replacements[m]}:"}
+  end
+
 end
diff --git a/lib/pretty_text.rb b/lib/pretty_text.rb
index ebe1503c977..aefd4bed006 100644
--- a/lib/pretty_text.rb
+++ b/lib/pretty_text.rb
@@ -246,23 +246,14 @@ module PrettyText
     end
   end
 
-  def self.emoji_unicode(text)
-    return text unless SiteSetting.enable_emoji?
-
-    Emoji.db.each do |e|
-      text.gsub!(e['emoji'], ":#{e['aliases'][0]}:")
-    end
-
-    text
-  end
-
   def self.cook(text, opts={})
     options = opts.dup
 
     # we have a minor inconsistency
     options[:topicId] = opts[:topic_id]
 
-    working_text = emoji_unicode(text.dup)
+    working_text = text.dup
+    Emoji.sub_unicode!(working_text) if SiteSetting.enable_emoji?
     sanitized = markdown(working_text, options)
 
     doc = Nokogiri::HTML.fragment(sanitized)