diff --git a/.rubocop.yml b/.rubocop.yml
index f1c83c7d773..852b2f71932 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -130,3 +130,8 @@ RSpec/EmptyExampleGroup:
     - 'spec/rubocop/cop/lint/script_permission_spec.rb'
     - 'spec/rubocop/cop/style/empty_else_spec.rb'
     - 'spec/rubocop/result_cache_spec.rb'
+
+Performance/CollectionLiteralInLoop:
+  Exclude:
+    - 'Rakefile'
+    - 'spec/**/*.rb'
diff --git a/Gemfile b/Gemfile
index 474776f05f6..3fdb9d4c734 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ gem 'memory_profiler', platform: :mri
 gem 'pry'
 gem 'rake', '~> 13.0'
 gem 'rspec', '~> 3.7'
-gem 'rubocop-performance', '~> 1.7.0'
+gem 'rubocop-performance', '~> 1.8.1'
 gem 'rubocop-rspec', '~> 1.43.2'
 # Workaround for cc-test-reporter with SimpleCov 0.18.
 # Stop upgrading SimpleCov until the following issue will be resolved.
diff --git a/lib/rubocop/config_validator.rb b/lib/rubocop/config_validator.rb
index 81fb923e69e..43b3673037a 100644
--- a/lib/rubocop/config_validator.rb
+++ b/lib/rubocop/config_validator.rb
@@ -18,6 +18,11 @@ class ConfigValidator
     # @api private
     NEW_COPS_VALUES = %w[pending disable enable].freeze
 
+    # @api private
+    CONFIG_CHECK_KEYS = %w[Enabled Safe SafeAutoCorrect AutoCorrect].to_set.freeze
+    CONFIG_CHECK_DEPARTMENTS = %w[pending override_department].freeze
+    private_constant :CONFIG_CHECK_KEYS, :CONFIG_CHECK_DEPARTMENTS
+
     def_delegators :@config, :smart_loaded_path, :for_all_cops
 
     def initialize(config)
@@ -202,13 +207,9 @@ def check_cop_config_value(hash, parent = nil)
       hash.each do |key, value|
         check_cop_config_value(value, key) if value.is_a?(Hash)
 
-        next unless %w[Enabled
-                       Safe
-                       SafeAutoCorrect
-                       AutoCorrect].include?(key) && value.is_a?(String)
+        next unless CONFIG_CHECK_KEYS.include?(key) && value.is_a?(String)
 
-        next if key == 'Enabled' &&
-                %w[pending override_department].include?(value)
+        next if key == 'Enabled' && CONFIG_CHECK_DEPARTMENTS.include?(value)
 
         raise ValidationError, msg_not_boolean(parent, key, value)
       end
diff --git a/lib/rubocop/cop/metrics/parameter_lists.rb b/lib/rubocop/cop/metrics/parameter_lists.rb
index 3c3dcb30ee3..cc25ec439d1 100644
--- a/lib/rubocop/cop/metrics/parameter_lists.rb
+++ b/lib/rubocop/cop/metrics/parameter_lists.rb
@@ -12,6 +12,9 @@ class ParameterLists < Base
         MSG = 'Avoid parameter lists longer than %<max>d parameters. ' \
               '[%<count>d/%<max>d]'
 
+        NAMED_KEYWORD_TYPES = %i[kwoptarg kwarg].freeze
+        private_constant :NAMED_KEYWORD_TYPES
+
         def on_args(node)
           count = args_count(node)
           return unless count > max_params
@@ -33,7 +36,7 @@ def args_count(node)
           if count_keyword_args?
             node.children.size
           else
-            node.children.count { |a| !%i[kwoptarg kwarg].include?(a.type) }
+            node.children.count { |a| !NAMED_KEYWORD_TYPES.include?(a.type) }
           end
         end
 
diff --git a/lib/rubocop/cop/style/trailing_underscore_variable.rb b/lib/rubocop/cop/style/trailing_underscore_variable.rb
index ef5ec64179e..5b8c7b4f771 100644
--- a/lib/rubocop/cop/style/trailing_underscore_variable.rb
+++ b/lib/rubocop/cop/style/trailing_underscore_variable.rb
@@ -36,6 +36,8 @@ class TrailingUnderscoreVariable < Base
         MSG = 'Do not use trailing `_`s in parallel assignment. ' \
               'Prefer `%<code>s`.'
         UNDERSCORE = '_'
+        DISALLOW = %i[lvasgn splat].freeze
+        private_constant :DISALLOW
 
         def on_masgn(node)
           ranges = unneeded_ranges(node)
@@ -64,7 +66,7 @@ def find_first_offense(variables)
 
         def find_first_possible_offense(variables)
           variables.reduce(nil) do |offense, variable|
-            break offense unless %i[lvasgn splat].include?(variable.type)
+            break offense unless DISALLOW.include?(variable.type)
 
             var, = *variable
             var, = *var
diff --git a/lib/rubocop/formatter/offense_count_formatter.rb b/lib/rubocop/formatter/offense_count_formatter.rb
index 96995e3ae7c..b805314eeee 100644
--- a/lib/rubocop/formatter/offense_count_formatter.rb
+++ b/lib/rubocop/formatter/offense_count_formatter.rb
@@ -67,7 +67,7 @@ def ordered_offense_counts(offense_counts)
       end
 
       def total_offense_count(offense_counts)
-        offense_counts.values.inject(0, :+)
+        offense_counts.values.sum
       end
     end
   end
diff --git a/lib/rubocop/formatter/worst_offenders_formatter.rb b/lib/rubocop/formatter/worst_offenders_formatter.rb
index d3a73921d8a..31d44da2328 100644
--- a/lib/rubocop/formatter/worst_offenders_formatter.rb
+++ b/lib/rubocop/formatter/worst_offenders_formatter.rb
@@ -55,7 +55,7 @@ def ordered_offense_counts(offense_counts)
       end
 
       def total_offense_count(offense_counts)
-        offense_counts.values.inject(0, :+)
+        offense_counts.values.sum
       end
     end
   end
diff --git a/lib/rubocop/options.rb b/lib/rubocop/options.rb
index 12e8ce9ead8..2d679b18b4c 100644
--- a/lib/rubocop/options.rb
+++ b/lib/rubocop/options.rb
@@ -242,6 +242,9 @@ def long_opt_symbol(args)
   # @api private
   class OptionsValidator
     class << self
+      SYNTAX_DEPARTMENTS = %w[Syntax Lint/Syntax].freeze
+      private_constant :SYNTAX_DEPARTMENTS
+
       # Cop name validation must be done later than option parsing, so it's not
       # called from within Options.
       def validate_cop_list(names)
@@ -253,7 +256,7 @@ def validate_cop_list(names)
         names.each do |name|
           next if cop_names.include?(name)
           next if departments.include?(name)
-          next if %w[Syntax Lint/Syntax].include?(name)
+          next if SYNTAX_DEPARTMENTS.include?(name)
 
           raise IncorrectCopNameError, format_message_from(name, cop_names)
         end