diff --git a/.rubocop.yml b/.rubocop.yml
index 81bd763e05..ee1c150bd9 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -312,5 +312,17 @@ Performance/DeleteSuffix:
 Performance/OpenStruct:
   Enabled: true
 
+Performance/InefficientHashSearch:
+  Enabled: true
+
+Performance/ConstantRegexp:
+  Enabled: true
+
+Performance/RedundantStringChars:
+  Enabled: true
+
+Performance/StringInclude:
+  Enabled: true
+
 Minitest/UnreachableAssertion:
   Enabled: true
diff --git a/actionpack/lib/action_controller/metal/http_authentication.rb b/actionpack/lib/action_controller/metal/http_authentication.rb
index 439ffd5c99..efb70eeb86 100644
--- a/actionpack/lib/action_controller/metal/http_authentication.rb
+++ b/actionpack/lib/action_controller/metal/http_authentication.rb
@@ -502,11 +502,14 @@ module ActionController
         array_params.each { |param| (param[1] || +"").gsub! %r/^"|"$/, "" }
       end
 
+      WHITESPACED_AUTHN_PAIR_DELIMITERS = /\s*#{AUTHN_PAIR_DELIMITERS}\s*/
+      private_constant :WHITESPACED_AUTHN_PAIR_DELIMITERS
+
       # This method takes an authorization body and splits up the key-value
       # pairs by the standardized <tt>:</tt>, <tt>;</tt>, or <tt>\t</tt>
       # delimiters defined in +AUTHN_PAIR_DELIMITERS+.
       def raw_params(auth)
-        _raw_params = auth.sub(TOKEN_REGEX, "").split(/\s*#{AUTHN_PAIR_DELIMITERS}\s*/)
+        _raw_params = auth.sub(TOKEN_REGEX, "").split(WHITESPACED_AUTHN_PAIR_DELIMITERS)
 
         if !_raw_params.first&.start_with?(TOKEN_KEY)
           _raw_params[0] = "#{TOKEN_KEY}#{_raw_params.first}"
diff --git a/actionpack/lib/action_dispatch/testing/assertions/response.rb b/actionpack/lib/action_dispatch/testing/assertions/response.rb
index fa6f35e67e..3256efc2af 100644
--- a/actionpack/lib/action_dispatch/testing/assertions/response.rb
+++ b/actionpack/lib/action_dispatch/testing/assertions/response.rb
@@ -30,7 +30,7 @@ module ActionDispatch
       def assert_response(type, message = nil)
         message ||= generate_response_message(type)
 
-        if RESPONSE_PREDICATES.keys.include?(type)
+        if RESPONSE_PREDICATES.key?(type)
           assert @response.public_send(RESPONSE_PREDICATES[type]), message
         else
           assert_equal AssertionResponse.new(type).code, @response.response_code, message
@@ -93,7 +93,7 @@ module ActionDispatch
         end
 
         def code_with_name(code_or_name)
-          if RESPONSE_PREDICATES.values.include?("#{code_or_name}?".to_sym)
+          if RESPONSE_PREDICATES.value?("#{code_or_name}?".to_sym)
             code_or_name = RESPONSE_PREDICATES.invert["#{code_or_name}?".to_sym]
           end
 
diff --git a/actionview/lib/action_view/template.rb b/actionview/lib/action_view/template.rb
index d912109221..5cae79973c 100644
--- a/actionview/lib/action_view/template.rb
+++ b/actionview/lib/action_view/template.rb
@@ -193,6 +193,9 @@ module ActionView
       @source.to_s
     end
 
+    LEADING_ENCODING_REGEXP = /\A#{ENCODING_FLAG}/
+    private_constant :LEADING_ENCODING_REGEXP
+
     # This method is responsible for properly setting the encoding of the
     # source. Until this point, we assume that the source is BINARY data.
     # If no additional information is supplied, we assume the encoding is
@@ -211,7 +214,7 @@ module ActionView
       # Look for # encoding: *. If we find one, we'll encode the
       # String in that encoding, otherwise, we'll use the
       # default external encoding.
-      if source.sub!(/\A#{ENCODING_FLAG}/, "")
+      if source.sub!(LEADING_ENCODING_REGEXP, "")
         encoding = magic_encoding = $1
       else
         encoding = Encoding.default_external
diff --git a/activerecord/lib/active_record/encryption/encryptable_record.rb b/activerecord/lib/active_record/encryption/encryptable_record.rb
index 04e84c44c8..d268b924f2 100644
--- a/activerecord/lib/active_record/encryption/encryptable_record.rb
+++ b/activerecord/lib/active_record/encryption/encryptable_record.rb
@@ -61,7 +61,7 @@ module ActiveRecord
 
         # Given a attribute name, it returns the name of the source attribute when it's a preserved one.
         def source_attribute_from_preserved_attribute(attribute_name)
-          attribute_name.to_s.sub(ORIGINAL_ATTRIBUTE_PREFIX, "") if /^#{ORIGINAL_ATTRIBUTE_PREFIX}/.match?(attribute_name)
+          attribute_name.to_s.sub(ORIGINAL_ATTRIBUTE_PREFIX, "") if attribute_name.start_with?(ORIGINAL_ATTRIBUTE_PREFIX)
         end
 
         private
diff --git a/activerecord/lib/active_record/test_fixtures.rb b/activerecord/lib/active_record/test_fixtures.rb
index 1ad2228478..fa6cdb71c0 100644
--- a/activerecord/lib/active_record/test_fixtures.rb
+++ b/activerecord/lib/active_record/test_fixtures.rb
@@ -59,7 +59,7 @@ module ActiveRecord
         unless fixture_set_names.empty?
           self.fixture_sets = fixture_sets.dup
           fixture_set_names.each do |fs_name|
-            key = fs_name.match?(%r{/}) ? -fs_name.to_s.tr("/", "_") : fs_name
+            key = fs_name.to_s.include?("/") ? -fs_name.to_s.tr("/", "_") : fs_name
             key = -key.to_s if key.is_a?(Symbol)
             fs_name = -fs_name.to_s if fs_name.is_a?(Symbol)
             fixture_sets[key] = fs_name
diff --git a/ci/test_run.rb b/ci/test_run.rb
index c3ba53ea7a..c270f46b2f 100644
--- a/ci/test_run.rb
+++ b/ci/test_run.rb
@@ -35,7 +35,7 @@ class TestRun
   end
 
   def completed?
-    @qunit_testresult.text =~ /Tests completed/
+    @qunit_testresult.text.include?("Tests completed")
   end
 
   def result
diff --git a/guides/rails_guides/epub.rb b/guides/rails_guides/epub.rb
index 149d69fa77..7a8c9e431a 100644
--- a/guides/rails_guides/epub.rb
+++ b/guides/rails_guides/epub.rb
@@ -49,7 +49,7 @@ module Epub # :nodoc:
     end
 
     def is_name_invalid(name)
-      (/[0-9]/ === name.chars.first)
+      name.match?(/\A\d/)
     end
 
     def fix_file_names(output_dir)
diff --git a/railties/lib/rails/generators/rails/benchmark/benchmark_generator.rb b/railties/lib/rails/generators/rails/benchmark/benchmark_generator.rb
index 7c76d6551c..fe83931947 100644
--- a/railties/lib/rails/generators/rails/benchmark/benchmark_generator.rb
+++ b/railties/lib/rails/generators/rails/benchmark/benchmark_generator.rb
@@ -6,6 +6,7 @@ module Rails
   module Generators
     class BenchmarkGenerator < NamedBase
       IPS_GEM_NAME = "benchmark-ips"
+      IPS_GEM_USED_REGEXP = /gem.*\b#{IPS_GEM_NAME}\b.*/
 
       argument :reports, type: :array, default: ["before", "after"]
 
@@ -21,7 +22,7 @@ module Rails
 
       def ips_installed?
         in_root do
-          return File.read("Gemfile").match?(/gem.*\b#{IPS_GEM_NAME}\b.*/)
+          return File.read("Gemfile").match?(IPS_GEM_USED_REGEXP)
         end
       end
     end
diff --git a/tasks/release.rb b/tasks/release.rb
index add25605f1..f63b01e170 100644
--- a/tasks/release.rb
+++ b/tasks/release.rb
@@ -314,7 +314,7 @@ module Announcement
     end
 
     def rc?
-      @version =~ /rc/
+      @version.include?("rc")
     end
   end
 end