Is Ruby hash lookup faster with symbol keys than string keys?

01_sym_vs_str.rb

require "benchmark/ips"
require "securerandom"

sym_hash = {}
str_hash = {}

1000.times do |i|
  # Generate a random key between 3 and 32 characters long
  SecureRandom.hex[0,rand(3..32)].tap do |key|
    str_hash[key] = i
    sym_hash[key.to_sym] = i
  end
end

sym_lookup = sym_hash.keys.shuffle
str_lookup = str_hash.keys.shuffle

Benchmark.ips do |x|
  x.report("symbol") {
    sym_lookup.each {|key| sym_hash[key] }
  }

  x.report("string") {
    str_lookup.each {|key| str_hash[key] }
  }

    x.compare!
end

02_result.txt

$ ruby -v
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]

$ ruby sym_vs_str.rb
Warming up --------------------------------------
              symbol     1.139k i/100ms
              string   752.000  i/100ms
Calculating -------------------------------------
              symbol     11.590k (± 3.9%) i/s -     58.089k in   5.019694s
              string      7.632k (± 3.7%) i/s -     38.352k in   5.031788s

Comparison:
              symbol:    11589.9 i/s
              string:     7632.3 i/s - 1.52x  slower