Kernel#load vs Kernel#eval

benchmark.rb

require 'benchmark'

Benchmark.bmbm do |bm|
  bm.report '1000 x Kernel#load wrap=false' do
    1000.times do
      load 'script.rb', false
    end
  end

  bm.report '1000 x Kernel#load wrap=true' do
    1000.times do
      load 'script.rb', true
    end
  end

  bm.report '1000 x Kernel#eval' do
    1000.times do
      eval File.read 'script.rb'
    end
  end
end

benchmark.txt

Rehearsal -----------------------------------------------------------------
1000 x Kernel#load wrap=false   0.660000   0.060000   0.720000 (  0.720393)
1000 x Kernel#load wrap=true    0.780000   0.060000   0.840000 (  0.848723)
1000 x Kernel#eval              0.600000   0.020000   0.620000 (  0.628405)
-------------------------------------------------------- total: 2.180000sec

                                    user     system      total        real
1000 x Kernel#load wrap=false   0.640000   0.060000   0.700000 (  0.693713)
1000 x Kernel#load wrap=true    0.800000   0.060000   0.860000 (  0.861577)
1000 x Kernel#eval              0.580000   0.020000   0.600000 (  0.603365)

ruby-version

ruby 2.1.5p273 (2014-11-13 revision 48405) [x86_64-darwin14.0]

script.rb

require 'set'

module FizzBuzz
  def fizz?
    self % 3 == 0
  end

  def buzz?
    self % 5 == 0
  end
end

class Fixnum
  include FizzBuzz
end

fizz = Set.new
buzz = Set.new

1000.times do |i|
  fizz.add i if i.fizz?
  buzz.add i if i.buzz?
end

fizzbuzz = fizz & buzz