Replace certain uses of 'gsub' with 'tr' or 'chomp' for a speed

improvement

lib/email/sender.rb

@@ -94,12 +94,12 @@ module Email
 
         # http://www.ietf.org/rfc/rfc2919.txt
         if topic && topic.category && !topic.category.uncategorized?
-          list_id = "<#{topic.category.name.downcase.gsub(' ', '-')}.#{host}>"
+          list_id = "<#{topic.category.name.downcase.tr(' ', '-')}.#{host}>"
 
           # subcategory case
           if !topic.category.parent_category_id.nil?
             parent_category_name = Category.find_by(id: topic.category.parent_category_id).name
-            list_id = "<#{topic.category.name.downcase.gsub(' ', '-')}.#{parent_category_name.downcase.gsub(' ', '-')}.#{host}>"
+            list_id = "<#{topic.category.name.downcase.tr(' ', '-')}.#{parent_category_name.downcase.tr(' ', '-')}.#{host}>"
           end
         else
           list_id = "<#{host}>"

lib/ip_addr.rb

@@ -16,7 +16,7 @@ class IPAddr
     (4 - parts.size).times { parts << '*' } # support strings like 192.*
     v = parts.join('.')
 
-    "#{v.gsub('*', '0')}/#{32 - (v.count('*') * 8)}"
+    "#{v.tr('*', '0')}/#{32 - (v.count('*') * 8)}"
   end
 
   def to_cidr_s

lib/slug.rb

@@ -20,9 +20,9 @@ module Slug
   private
 
   def self.ascii_generator(string)
-    string.gsub("'", "")
+    string.tr("'", "")
           .parameterize
-          .gsub("_", "-")
+          .tr("_", "-")
   end
 
   def self.encoded_generator(string)