diff --git a/lib/rubocop/cop/rspec/cop.rb b/lib/rubocop/cop/rspec/cop.rb
index d9f09d4f1..a646c5e92 100644
--- a/lib/rubocop/cop/rspec/cop.rb
+++ b/lib/rubocop/cop/rspec/cop.rb
@@ -45,7 +45,7 @@ def relevant_rubocop_rspec_file?(file)
         end
 
         def rspec_pattern
-          if rspec_pattern_config?
+          @rspec_pattern ||= if rspec_pattern_config?
             Regexp.union(rspec_pattern_config.map(&Regexp.public_method(:new)))
           else
             DEFAULT_PATTERN_RE