Is it quicker to concatenate individual elements, or construct a new array and add that to the existing one?

3-element-benchmark-array-concatenation.rb

require 'benchmark'
repeats = 3
iterations = 1_000_000

def check(repeats, &block)
  times = []
  repeats.times do
    times << Benchmark.realtime(&block)
  end
  # Return the average
  (times.reduce(&:+) / repeats).round(5)
end

result = check(repeats) do
  iterations.times do
    initial = []
    initial << :tom << :dick << :harry
  end
end
puts "Method A: #{result}"

result = check(repeats) do
  iterations.times do
    initial = []
    initial += [:tom, :dick, :harry]
  end
end
puts "Method B: #{result}"

6-element-results

PaulSmith:~ paul$ ruby Desktop/bench.rb 
Method A: 0.16236
Method B: 0.18056

9-element-array-concatenation.rb

require 'benchmark'
repeats = 3
iterations = 1_000_000

def check(repeats, &block)
  times = []
  repeats.times do
    times << Benchmark.realtime(&block)
  end
  # Return the average
  (times.reduce(&:+) / repeats).round(5)
end

result = check(repeats) do
  iterations.times do
    initial = []
    initial << :tom << :dick << :harry << :huey << :dewey << :louie << :rita << :sue << :bob_too
  end
end
puts "Method A: #{result}"

result = check(repeats) do
  iterations.times do
    initial = []
    initial += [:tom, :dick, :harry, :huey, :dewey, :louie, :rita, :sue, :bob_too]
  end
end
puts "Method B: #{result}"

9-element-results

PaulSmith:~ paul$ ruby Desktop/bench.rb 
Method A: 0.55013
Method B: 0.53659