1 files changed, 5 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/name_error.rb b/activesupport/lib/active_support/core_ext/name_error.rb
index 6b447d772b..97a38efde2 100644
--- a/activesupport/lib/active_support/core_ext/name_error.rb
+++ b/activesupport/lib/active_support/core_ext/name_error.rb
@@ -8,6 +8,11 @@ class NameError
   #   end
   #   # => "HelloWorld"
   def missing_name
+    # Since ruby v2.3.0 `did_you_mean` gem is loaded by default.
+    # It extends NameError#message with spell corrections which are SLOW.
+    # We should use original_message message instead.
+    message = respond_to?(:original_message) ? original_message : self.message
+
     if /undefined local variable or method/ !~ message
       $1 if /((::)?([A-Z]\w*)(::[A-Z]\w*)*)$/ =~ message
     end