Array.uniq.to_set vs Array.to_set

gistfile1.rb

require 'benchmark/ips'
require 'set'

#init array
arr = Array.new
1000.times do
  arr << (rand * 20).to_i
end

Benchmark.ips do |x|
  x.config(:time => 10, :warmup => 2)

  x.report("Array") do
    arr.uniq.to_set
  end

  x.report("Set") do
    arr.to_set
  end

  x.compare!
end

Comparison:
               Array:    23503.0 i/s
                 Set:     5785.4 i/s - 4.06x slower