Merge pull request rails#46586 from SeanLF/main

Improve `ActiveSupport::Inflector.transliterate` performance [Fix rails#46569]

Author: byroot

activesupport/lib/active_support/inflector/transliterate.rb

@@ -62,10 +62,12 @@ module Inflector
     # Transliteration is restricted to UTF-8, US-ASCII, and GB18030 strings.
     # Other encodings will raise an ArgumentError.
     def transliterate(string, replacement = "?", locale: nil)
-      string = string.dup if string.frozen?
       raise ArgumentError, "Can only transliterate strings. Received #{string.class.name}" unless string.is_a?(String)
       raise ArgumentError, "Cannot transliterate strings with #{string.encoding} encoding" unless ALLOWED_ENCODINGS_FOR_TRANSLITERATE.include?(string.encoding)
 
+      string = string.dup if string.frozen?
+      return string if string.ascii_only?
+
       input_encoding = string.encoding
 
       # US-ASCII is a subset of UTF-8 so we'll force encoding as UTF-8 if