Merge pull request #15313 from andreychernih/time-with-zone-string-conversion-speed-up

Speed-up TimeWithZone to String conversion

activesupport/lib/active_support/time_with_zone.rb

@@ -353,6 +353,14 @@ module ActiveSupport
       initialize(variables[0].utc, ::Time.find_zone(variables[1]), variables[2].utc)
     end
 
+    # respond_to_missing? is not called in some cases, such as when type conversion is
+    # performed with Kernel#String
+    def respond_to?(sym, include_priv = false)
+      # ensure that we're not going to throw and rescue from NoMethodError in method_missing which is slow
+      return false if sym.to_sym == :to_str
+      super
+    end
+
     # Ensure proxy class responds to all methods that underlying time instance
     # responds to.
     def respond_to_missing?(sym, include_priv)