Similar to #17099, Enumerable#reverse allocates an extra array. Enumerable#reverse_each yields each value without allocating an extra array. This is the reason why Enumerable#reverse_each exists. It is also about 17% faster.

Benchmark

require 'benchmark/ips'

ARRAY = (1..100).to_a

def slow
  ARRAY.reverse.each{|x| x}
end

def fast
  ARRAY.reverse_each{|x| x}
end

Benchmark.ips do |x|
  x.report('slow') { slow }
  x.report('fast') { fast }
end

Ruby 2.1.2

slow 156173.2 (±9.2%) i/s - 770040 in 5.009112s
fast 182859.3 (±7.8%) i/s - 914486 in 5.035575s