Array() vs #flatten

bm.rb

require 'benchmark'

n = 1_000_000

Benchmark.bm do |x|
  x.report('[[1]]') { n.times { [[1]].flatten } }
  x.report('Array([1])') { n.times { Array([1]) } }
  x.report('[1]') { n.times { [1].flatten } }
  x.report('Array(1)') { n.times { Array(1) } }
end

#             user       system     total       real
# [[1]]       1.470000   0.020000   1.490000 (  1.493567)
# Array([1])  0.280000   0.000000   0.280000 (  0.276987)
# [1]         1.010000   0.020000   1.030000 (  1.037248)
# Array(1)    0.370000   0.000000   0.370000 (  0.369389)