Optimize uri normalization (#4212)

* Add dependency on idn-ruby to speed up URI normalization

* Use normalized_host instead of normalize.host when applicable

When we are only interested in the normalized host, calling normalized_host
avoids normalizing the other components of the URI as well as creating a
new object

app/services/concerns/author_extractor.rb

@@ -14,7 +14,7 @@ module AuthorExtractor
 
       return nil if username.blank? || uri.blank?
 
-      domain = Addressable::URI.parse(uri).normalize.host
+      domain = Addressable::URI.parse(uri).normalized_host
       acct   = "#{username}@#{domain}"
     end