sum_each_inject.rb

require 'benchmark'

puts "ruby-#{RUBY_VERSION}"

Benchmark.bm(10) do |x|
  array = (10 ** 5).times.to_a

  x.report 'sum' do |x|
    array.sum {|i| i * 2 }
  end

  x.report 'each' do |x|
    ans = 0
    array.each {|i| ans += i * 2 }
  end

  x.report 'inject' do |x|
    array.inject(0) {|acc, i| acc + i * 2 }
  end
end

__END__
ruby-2.7.1
                 user     system      total        real
sum          0.001611   0.000000   0.001611 (  0.001606)
each         0.001996   0.000000   0.001996 (  0.001997)
inject       0.002512   0.000000   0.002512 (  0.002512)

ruby-3.2.2
                 user     system      total        real
sum          0.001578   0.000526   0.002104 (  0.002100)
each         0.001657   0.000553   0.002210 (  0.002209)
inject       0.002884   0.000000   0.002884 (  0.002884)