lookup.rb

require 'benchmark'

MAX = 1000
RANGE = (0..MAX).to_a

array = []
hash = {}

RANGE.each do |i|
  array[i] = i
  hash[i] = i
end

TIMES = 10_000_000

Benchmark.bm do |x|
  x.report { TIMES.times { key = RANGE.sample; array[key] } }
  x.report { TIMES.times { key = RANGE.sample; hash[key] } }
end

result.txt

       user     system      total        real
   1.050000   0.000000   1.050000 (  1.049729)
   1.470000   0.000000   1.470000 (  1.465718)