bench.rb

require 'benchmark/ips'

NUMBERS = [10, 20, 30]

def iterate_with_return
  NUMBERS.each do |number|
    return number if number == 20
  end
end

def iterate_with_break
  found = nil

  NUMBERS.each do |number|
    if number == 20
      found = number
      break
    end
  end

  found
end

Benchmark.ips do |bench|
  bench.report 'return' do
    iterate_with_return
  end

  bench.report 'break' do
    iterate_with_break
  end

  bench.compare!
end

output.txt

Calculating -------------------------------------
              return    84.624k i/100ms
               break    86.813k i/100ms
-------------------------------------------------
              return      2.217M (± 8.8%) i/s -     11.001M
               break      2.140M (± 8.1%) i/s -     10.678M

Comparison:
              return:  2216760.7 i/s
               break:  2140461.7 i/s - 1.04x slower