Initialize symbols instead of mapping to_sym on the set of strings

[rodzyn]

We have %i so no need to use %w with map(&:to_sym)

require 'benchmark/ips'
require 'set'

Benchmark.ips do |x|
  x.report('%w') do
    Set.new %w(
      @_action_name @_response_body @_formats @_prefixes @_config
      @_view_context_class @_view_renderer @_lookup_context
      @_routes @_db_runtime
    ).map(&:to_sym)
  end

  x.report('%i') do
    Set.new %i(
      @_action_name @_response_body @_formats @_prefixes @_config
      @_view_context_class @_view_renderer @_lookup_context
      @_routes @_db_runtime
    )
  end
end

Calculating -------------------------------------
                  %w     6.162k i/100ms
                  %i     8.277k i/100ms
-------------------------------------------------
                  %w     63.862k (±10.4%) i/s -    320.424k
                  %i     84.348k (±12.2%) i/s -    422.127k